import requests
import time

# Profile Service
class ProfileService:
    def __init__(self):
        self.profiles = {}
        
    def save_profile(self, user_id, profile):
        self.profiles[user_id] = profile
        
    def get_profile(self, user_id):
        return self.profiles.get(user_id)
        
# Get Location Service
class GetLocationService:
    def __init__(self, api_key):
        self.api_key = api_key
        
    def get_lat_long(self, address):
        url = f'https://maps.googleapis.com/maps/api/geocode/json?address={address}&key={self.api_key}'
        response = requests.get(url)
        response_json = response.json()
        if response_json['status'] == 'OK':
            location = response_json['results'][0]['geometry']['location']
            return (location['lat'], location['lng'])
        else:
            return None
        
# Traffic Update Service
class TrafficUpdateService:
    def __init__(self, api_key):
        self.api_key = api_key
        
    def get_traffic_update(self, origin, destination):
        url = f'https://maps.googleapis.com/maps/api/directions/json?origin={origin}&destination={destination}&key={self.api_key}&departure_time=now&traffic_model=best_guess'
        response = requests.get(url)
        response_json = response.json()
        if response_json['status'] == 'OK':
            traffic = response_json['routes'][0]['legs'][0]['duration_in_traffic']['text']
            return traffic
        else:
            return None
        
# Route Processing Service
class RouteProcessingService:
    def __init__(self, api_key):
        self.api_key = api_key
        
    def get_distance(self, origin, destination):
        url = f'https://maps.googleapis.com/maps/api/distancematrix/json?origins={origin}&destinations={destination}&key={self.api_key}'
        response = requests.get(url)
        response_json = response.json()
        if response_json['status'] == 'OK':
            distance = response_json['rows'][0]['elements'][0]['distance']['text']
            return distance
        else:
            return None
        
# Tracking Service
class TrackingService:
    def __init__(self):
        self.locations = {}
        
    def track_user(self, user_id, location):
        self.locations[user_id] = location
        
    def get_user_location(self, user_id):
        return self.locations.get(user_id)
        
# User Location Service
class UserLocationService:
    def __init__(self, api_key):
        self.api_key = api_key
        
    def continuously_track_location(self, user_id):
        while True:
            location = get_location(user_id)
            track_user(user_id, location)
            time.sleep(60)
            
    def get_location(self, user_id):
        url = f'https://www.googleapis.com/geolocation/v1/geolocate?key={self.api_key}'
        response = requests.post(url)
        response_json = response.json()
        if response_json.get('location'):
            return response_json['location']
        else:
            return None
        
# Route Update Service
class RouteUpdateService:
    def __init__(self, api_key):
        self.api_key = api_key
     

def update_route(origin, destination, waypoints=[], mode='driving'):
    # Get directions using Google Maps API
    directions = gmaps.directions(origin, destination, mode=mode, waypoints=waypoints)
    
    # Extract route information
    route = directions[0]['legs'][0]
    distance = route['distance']['value']  # meters
    duration = route['duration']['value']  # seconds
    steps = route['steps']
    
    # Return updated route information
    return distance, duration, steps

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class Location {
    private String name;
    private double latitude;
    private double longitude;

    public Location(String name, double latitude, double longitude) {
        this.name = name;
        this.latitude = latitude;
        this.longitude = longitude;
    }

    public String getName() {
        return name;
    }

    public double getLatitude() {
        return latitude;
    }

    public double getLongitude() {
        return longitude;
    }
}

class User {
    private String username;
    private Map<String, Location> savedLocations;

    public User(String username) {
        this.username = username;
        this.savedLocations = new HashMap<>();
    }

    public String getUsername() {
        return username;
    }

    public Map<String, Location> getSavedLocations() {
        return savedLocations;
    }

    public void saveLocation(String locationName, double latitude, double longitude) {
        Location location = new Location(locationName, latitude, longitude);
        savedLocations.put(locationName, location);
        System.out.println("Location saved successfully: " + locationName);
    }

    public void deleteLocation(String locationName) {
        if (savedLocations.containsKey(locationName)) {
            savedLocations.remove(locationName);
            System.out.println("Location deleted successfully: " + locationName);
        } else {
            System.out.println("Location not found: " + locationName);
        }
    }
}

class GoogleMapsSystem {
    private Map<String, User> users;

    public GoogleMapsSystem() {
        this.users = new HashMap<>();
    }

    public void registerUser(String username) {
        if (users.containsKey(username)) {
            System.out.println("Username already exists: " + username);
        } else {
            User user = new User(username);
            users.put(username, user);
            System.out.println("User registered successfully: " + username);
        }
    }

    public User loginUser(String username) {
        if (users.containsKey(username)) {
            User user = users.get(username);
            System.out.println("User logged in successfully: " + username);
            return user;
        }
        System.out.println("User not found: " + username);
        return null;
    }
}

public class GoogleMapsApp {
    public static void main(String[] args) {
        GoogleMapsSystem googleMaps = new GoogleMapsSystem();

        // Register users
        googleMaps.registerUser("user1");
        googleMaps.registerUser("user2");

        // Login with a user
        User user = googleMaps.loginUser("user1");
        if (user != null) {
            // Save a location
            user.saveLocation("Home", 37.7749, -122.4194);

            // Delete a location
            user.deleteLocation("Work");
        }
    }
}

Endpoint: /geocode
Method: GET
Parameters:
- address (required): the address to be geocoded
Response:
{
    "latitude": 40.712776,
    "longitude": -74.005974
}

Endpoint: /route
Method: GET
Parameters:
- origin (required): the starting point of the route
- destination (required): the ending point of the route
Response:
{
    "distance": 12.3, # in kilometers
    "duration": 25, # in minutes
    "steps": [
        {
            "distance": 1.2, # in kilometers
            "duration": 5, # in minutes
            "instructions": "Turn left onto Main Street",
            "start_location": {
                "latitude": 40.712776,
                "longitude": -74.005974
            },
            "end_location": {
                "latitude": 40.719778,
                "longitude": -74.003902
            }
        },
        ...
    ]
}

Endpoint: /reverse-geocode
Method: GET
Parameters:
- latitude (required): the latitude coordinate
- longitude (required): the longitude coordinate
Response:
{
    "address": "123 Main St, New York, NY 10001"
}

Endpoint: /traffic-update
Method: GET
Parameters:
- route (required): the route to get traffic information for
Response:
{
    "traffic_data": [
        {
            "distance": 1.2, # in kilometers
            "duration": 5, # in minutes
            "traffic": "light",
            "start_location": {
                "latitude": 40.712776,
                "longitude": -74.005974
            },
            "end_location": {
                "latitude": 40.719778,
                "longitude": -74.003902
            }
        },
        ...
    ]
}

Endpoint: /place-search
Method: GET
Parameters:
- location (required): the location to search near
- radius (optional): the radius to search within (default is 1000 meters)
- keyword (optional): a keyword to search for (e.g. "pizza", "gas station")
Response:
{
    "places": [
        {
            "name": "Joe's Pizza",
            "location": {
                "latitude": 40.712776,
                "longitude": -74.005974
            },
            "address": "123 Main St, New York, NY 10001",
            "rating": 4.5
        },
        ...
    ]
}

import redis

# Connect to Redis server
r = redis.Redis(host='localhost', port=6379, db=0)

# Store map data
def store_map_data(map_id, map_data):
    r.set(map_id, map_data)

# Retrieve map data
def retrieve_map_data(map_id):
    return r.get(map_id)

# Usage example
map_id = 'map1'
map_data = '...'
store_map_data(map_id, map_data)
retrieved_data = retrieve_map_data(map_id)
print(retrieved_data)

from geopy.geocoders import Nominatim

# Create a geocoder instance
geolocator = Nominatim(user_agent='my_geocoder')

# Geocoding: Address to Coordinates
def geocode(address):
    location = geolocator.geocode(address)
    return (location.latitude, location.longitude)

# Reverse Geocoding: Coordinates to Address
def reverse_geocode(latitude, longitude):
    location = geolocator.reverse((latitude, longitude))
    return location.address

# Usage example
address = '1600 Amphitheatre Parkway, Mountain View, CA'
coordinates = geocode(address)
print(coordinates)
retrieved_address = reverse_geocode(coordinates[0], coordinates[1])
print(retrieved_address)

import requests

# Graphhopper API endpoint
endpoint = 'https://graphhopper.com/api/1/route'

# Calculate route
def calculate_route(start, end):
    params = {
        'key': 'YOUR_API_KEY',
        'point': [start, end],
        'type': 'json'
    }
    response = requests.get(endpoint, params=params)
    route_data = response.json()
    return route_data['paths'][0]['points']

# Usage example
start = '51.5074, -0.1278'  # London coordinates
end = '48.8566, 2.3522'     # Paris coordinates
route = calculate_route(start, end)
print(route)

import requests

# Google Maps Directions API endpoint
endpoint = 'https://maps.googleapis.com/maps/api/directions/json'

# Get real-time traffic information
def get_traffic_info(origin, destination):
    params = {
        'origin': origin,
        'destination': destination,
        'key': 'YOUR_API_KEY',
        'departure_time': 'now',
        'traffic_model': 'best_guess',
        'mode': 'driving'
    }
    response = requests.get(endpoint, params=params)
    traffic_data = response.json()
    return traffic_data['routes'][0]['legs'][0]['duration_in_traffic']

# Usage example
origin = 'San Francisco, CA'
destination = 'Los Angeles, CA'
traffic_info = get_traffic_info(origin, destination)
print(traffic_info)

# POI data storage
poi_data = {
    'restaurant1': {
        'name': 'Restaurant A',
        'location': (latitude1, longitude1),
        'reviews': [review1, review2, review3],
        'rating': 4.5
    },
    'hotel1': {
        'name': 'Hotel X',
        'location': (latitude2, longitude2),
        'reviews': [review4, review5],
        'rating': 3.8
    },
    # Additional POI entries
}

# Search for nearby POIs
def search_nearby_pois(latitude, longitude, radius):
    nearby_pois = []
    for poi_id, poi_info in poi_data.items():
        poi_latitude, poi_longitude = poi_info['location']
        distance = calculate_distance(latitude, longitude, poi_latitude, poi_longitude)
        if distance <= radius:
            nearby_pois.append(poi_info)
    return nearby_pois

# Usage example
user_latitude = 37.7749
user_longitude = -122.4194
search_radius = 1000  # meters
nearby_pois = search_nearby_pois(user_latitude, user_longitude, search_radius)
for poi in nearby_pois:
    print(poi['name'], poi['rating'])

import requests

# Google Street View Image API endpoint
endpoint = 'https://maps.googleapis.com/maps/api/streetview'

# Get street view image
def get_street_view_image(location, size, heading, pitch, fov):
    params = {
        'location': location,
        'size': size,
        'heading': heading,
        'pitch': pitch,
        'fov': fov,
        'key': 'YOUR_API_KEY'
    }
    response = requests.get(endpoint, params=params)
    image_data = response.content
    return image_data

# Usage example
location = '40.7128,-74.0060'  # New York City coordinates
image_size = '600x400'
image_heading = 90
image_pitch = 0
image_fov = 90
street_view_image = get_street_view_image(location, image_size, image_heading, image_pitch, image_fov)
# Save or display the image

from flask import Flask, request
import gettext

app = Flask(__name__)

# Configure localization
locales_dir = 'locales'
default_locale = 'en_US'

@babel.localeselector
def get_locale():
    user_locale = request.headers.get('Accept-Language')
    if user_locale:
        return user_locale
    return default_locale

# Load translations
translations = gettext.translation('messages', localedir=locales_dir, languages=[default_locale])
translations.install()

# Define localized routes
@app.route('/')
def home():
    welcome_message = _('Welcome to our Maps application!')
    return welcome_message

@app.route('/about')
def about():
    about_message = _('About us')
    return about_message

# Usage example
if __name__ == '__main__':
    app.run()

import mapbox

# Create a Mapbox client
access_token = 'YOUR_ACCESS_TOKEN'
client = mapbox.Mapbox(access_token)

# Offline map caching
def cache_map_area(center_latitude, center_longitude, zoom_level, width, height):
    area = {
        'type': 'Feature',
        'properties': {},
        'geometry': {
            'type': 'Point',
            'coordinates': [center_longitude, center_latitude]
        }
    }
    options = {
        'zoom': zoom_level,
        'width': width,
        'height': height,
        'padding': 0.1,
        'optimize': True
    }
    response = client.static_image([area], **options)
    with open('offline_map.png', 'wb') as f:
        f.write(response.content)

# Usage example
center_latitude = 37.7749
center_longitude = -122.4194
zoom_level = 12
map_width = 800
map_height = 600
cache_map_area(center_latitude, center_longitude, zoom_level, map_width, map_height)

import requests

# Google Places API endpoint
endpoint = 'https://maps.googleapis.com/maps/api/place/nearbysearch/json'

# Get personalized place recommendations
def get_place_recommendations(latitude, longitude, radius, keyword):
    params = {
        'location': f'{latitude},{longitude}',
        'radius': radius,
        'keyword': keyword,
        'key': 'YOUR_API_KEY'
    }
    response = requests.get(endpoint, params=params)
    recommendations_data = response.json()
    return recommendations_data['results']

# Usage example
user_latitude = 37.7749
user_longitude = -122.4194
search_radius = 1000  # meters
keyword = 'coffee'
recommendations = get_place_recommendations(user_latitude, user_longitude, search_radius, keyword)
for recommendation in recommendations:
    print(recommendation['name'], recommendation['rating'])

import requests

# Google Maps Distance Matrix API endpoint
endpoint = 'https://maps.googleapis.com/maps/api/distancematrix/json'

# Calculate distance and duration
def calculate_distance_duration(origins, destinations):
    params = {
        'origins': '|'.join(origins),
        'destinations': '|'.join(destinations),
        'key': 'YOUR_API_KEY'
    }
    response = requests.get(endpoint, params=params)
    distance_data = response.json()
    return distance_data['rows']

# Usage example
origins = ['San Francisco, CA', 'Los Angeles, CA']
destinations = ['New York, NY', 'Chicago, IL']
distance_matrix = calculate_distance_duration(origins, destinations)
for row in distance_matrix:
    print(row['elements'])

import redis

# Connect to Redis server
r = redis.Redis(host='localhost', port=6379, db=0)

# Cache map tile
def cache_map_tile(tile_id, tile_data):
    r.set(tile_id, tile_data)

# Retrieve map tile from cache
def retrieve_map_tile(tile_id):
    return r.get(tile_id)

# Usage example
tile_id = 'tile_123'
tile_data = '...'
cache_map_tile(tile_id, tile_data)
retrieved_tile = retrieve_map_tile(tile_id)
print(retrieved_tile)

import requests

# CDN endpoint for map tiles
cdn_endpoint = 'https://cdn.example.com/tiles/'

# Retrieve map tile from CDN
def retrieve_map_tile(tile_id):
    url = cdn_endpoint + tile_id
    response = requests.get(url)
    return response.content

# Usage example
tile_id = 'tile_123'
retrieved_tile = retrieve_map_tile(tile_id)
print(retrieved_tile)

# Map tile storage
map_tiles = {}

# Store map tile
def store_map_tile(tile_id, tile_data):
    map_tiles[tile_id] = tile_data

# Retrieve map tile
def retrieve_map_tile(tile_id):
    return map_tiles.get(tile_id)

# Usage example
tile_id = 'tile_123'
tile_data = '...'
store_map_tile(tile_id, tile_data)
retrieved_tile = retrieve_map_tile(tile_id)
print(retrieved_tile)

from geopy.geocoders import Nominatim

# Create a geocoder instance
geolocator = Nominatim(user_agent='my_geocoder')

# Geocode address to coordinates
def geocode_address(address):
    location = geolocator.geocode(address)
    return location.latitude, location.longitude

# Reverse geocode coordinates to address
def reverse_geocode_coordinates(latitude, longitude):
    location = geolocator.reverse((latitude, longitude))
    return location.address

# Usage example
address = '1600 Amphitheatre Parkway, Mountain View, CA'
latitude, longitude = geocode_address(address)
print(latitude, longitude)

reverse_address = reverse_geocode_coordinates(latitude, longitude)
print(reverse_address)

import requests

# Google Maps Directions API endpoint
endpoint = 'https://maps.googleapis.com/maps/api/directions/json'

# Calculate route and directions
def calculate_route(origin, destination, mode='driving'):
    params = {
        'origin': origin,
        'destination': destination,
        'mode': mode,
        'key': 'YOUR_API_KEY'
    }
    response = requests.get(endpoint, params=params)
    directions_data = response.json()
    return directions_data['routes']

# Usage example
origin = 'San Francisco, CA'
destination = 'Los Angeles, CA'
routes = calculate_route(origin, destination)
for route in routes:
    print(route['summary'])
    for step in route['legs'][0]['steps']:
        print(step['html_instructions'])

class User:
    def __init__(self, user_id, username, password):
        self.user_id = user_id
        self.username = username
        self.password = password
        # Other user attributes
    
class Flight:
    def __init__(self, flight_id, airline, departure_time, arrival_time, origin, destination, price):
        self.flight_id = flight_id
        self.airline = airline
        self.departure_time = departure_time
        self.arrival_time = arrival_time
        self.origin = origin
        self.destination = destination
        self.price = price
        # Other flight attributes
    
class Hotel:
    def __init__(self, hotel_id, name, location, price):
        self.hotel_id = hotel_id
        self.name = name
        self.location = location
        self.price = price
        # Other hotel attributes
    
class CarRental:
    def __init__(self, car_rental_id, name, location, price):
        self.car_rental_id = car_rental_id
        self.name = name
        self.location = location
        self.price = price
        # Other car rental attributes

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/flights/search', methods=['POST'])
def search_flights():
    # Extract request parameters
    origin = request.json['origin']
    destination = request.json['destination']
    departure_date = request.json['departure_date']
    passenger_count = request.json['passenger_count']

    # Perform flight search logic
    # ... (implementation omitted)

    # Prepare and return the response
    flights = [
        {
            "airline": "British Airways",
            "flight_number": "BA123",
            "departure_time": "2023-07-15T10:00:00",
            "arrival_time": "2023-07-15T16:00:00",
            "price": 500.00
        },
        {
            "airline": "Delta Air Lines",
            "flight_number": "DL456",
            "departure_time": "2023-07-15T11:30:00",
            "arrival_time": "2023-07-15T18:30:00",
            "price": 550.00
        }
    ]

    response = {"flights": flights}
    return jsonify(response)

@app.route('/flights/<flight_id>/details', methods=['GET'])
def get_flight_details(flight_id):
    # Retrieve flight details based on flight_id
    # ... (implementation omitted)

    # Prepare and return the response
    flight_details = {
        "airline": "British Airways",
        "flight_number": "BA123",
        "departure_time": "2023-07-15T10:00:00",
        "arrival_time": "2023-07-15T16:00:00",
        "origin": "New York",
        "destination": "London",
        "price": 500.00,
        "available_seats": 100
    }

    return jsonify(flight_details)

if __name__ == '__main__':
    app.run()

def search_flights(destination, departure_date, budget):
    # Perform flight search logic
    # ...
    
    # Return the search results
    flights = [
        {
            "airline": "British Airways",
            "flight_number": "BA123",
            "departure_time": "2023-07-15T10:00:00",
            "arrival_time": "2023-07-15T16:00:00",
            "price": 500.00
        },
        {
            "airline": "Delta Air Lines",
            "flight_number": "DL456",
            "departure_time": "2023-07-15T11:30:00",
            "arrival_time": "2023-07-15T18:30:00",
            "price": 550.00
        }
    ]
    
    return flights

def search_hotels(destination, check_in_date, check_out_date):
    # Perform hotel search logic
    # ...
    
    # Return the search results
    hotels = [
        {
            "name": "Hotel A",
            "location": "New York",
            "price": 150.00
        },
        {
            "name": "Hotel B",
            "location": "London",
            "price": 200.00
        }
    ]
    
    return hotels

def search_car_rentals(destination, start_date, end_date):
    # Perform car rental search logic
    # ...
    
    # Return the search results
    car_rentals = [
        {
            "name": "Car Rental X",
            "location": "New York",
            "price": 50.00
        },
        {
            "name": "Car Rental Y",
            "location": "London",
            "price": 70.00
        }
    ]
    
    return car_rentals

def compare_prices(flights, hotels, car_rentals):
    # Perform price comparison logic
    # ...
    
    # Return the comparison results
    comparison_results = {
        "flights": flights,
        "hotels": hotels,
        "car_rentals": car_rentals
    }
    
    return comparison_results

def explore_alternative_dates(origin, destination, departure_date):
    # Perform alternative dates search logic
    # ...
    
    # Return the alternative dates
    alternative_dates = [
        "2023-07-16",
        "2023-07-17",
        "2023-07-18"
    ]
    
    return alternative_dates

def explore_nearby_airports(location):
    # Perform nearby airports search logic
    # ...
    
    # Return the nearby airports
    nearby_airports = [
        "JFK Airport",
        "Newark Liberty International Airport",
        "LaGuardia Airport"
    ]
    
    return nearby_airports

from datetime import datetime

class User:
    def __init__(self, user_id, username, email, password):
        self.user_id = user_id
        self.username = username
        self.email = email
        self.password = password

class Course:
    def __init__(self, course_id, name, description, difficulty_level):
        self.course_id = course_id
        self.name = name
        self.description = description
        self.difficulty_level = difficulty_level

class Lesson:
    def __init__(self, lesson_id, course_id, name):
        self.lesson_id = lesson_id
        self.course_id = course_id
        self.name = name

class Exercise:
    def __init__(self, exercise_id, lesson_id, name):
        self.exercise_id = exercise_id
        self.lesson_id = lesson_id
        self.name = name

class User_Course_Progress:
    def __init__(self, user_id, course_id, progress):
        self.user_id = user_id
        self.course_id = course_id
        self.progress = progress

class User_Lesson_Progress:
    def __init__(self, user_id, lesson_id, progress):
        self.user_id = user_id
        self.lesson_id = lesson_id
        self.progress = progress

class User_Exercise_Progress:
    def __init__(self, user_id, exercise_id, progress):
        self.user_id = user_id
        self.exercise_id = exercise_id
        self.progress = progress

class CourseService:
    def __init__(self):
        self.courses = []

    def create_course(self, course_id, name, description, difficulty_level):
        course = Course(course_id, name, description, difficulty_level)
        self.courses.append(course)

    def get_course_details(self, course_id):
        for course in self.courses:
            if course.course_id == course_id:
                return course

class LessonService:
    def __init__(self):
        self.lessons = []

    def create_lesson(self, lesson_id, course_id, name):
        lesson = Lesson(lesson_id, course_id, name)
        self.lessons.append(lesson)

    def get_lesson_details(self, lesson_id):
        for lesson in self.lessons:
            if lesson.lesson_id == lesson_id:
                return lesson

class ExerciseService:
    def __init__(self):
        self.exercises = []

    def create_exercise(self, exercise_id, lesson_id, name):
        exercise = Exercise(exercise_id, lesson_id, name)
        self.exercises.append(exercise)

    def get_exercise_details(self, exercise_id):
        for exercise in self.exercises:
            if exercise.exercise_id == exercise_id:
                return exercise

class UserService:
    def __init__(self):
        self.users = []

    def register_user(self, user_id, username, email, password):
        user = User(user_id, username, email, password)
        self.users.append(user)

    def authenticate_user(self, username, password):
        for user in self.users:
            if user.username == username and user.password == password:
                return user

    def get_user_profile(self, user_id):
        for user in self.users:
            if user.user_id == user_id:
                return user

class ProgressTrackingService:
    def __init__(self):
        self.user_course_progress = []
        self.user_lesson_progress = []
        self.user_exercise_progress = []

    def update_course_progress(self, user_id, course_id, progress):
        user_course_progress = User_Course_Progress(user_id, course_id, progress)
        self.user_course_progress.append(user_course_progress)

    def update_lesson_progress(self, user_id, lesson_id, progress):
        user_lesson_progress = User_Lesson_Progress(user_id, lesson_id, progress)
        self.user_lesson_progress.append(user_lesson_progress)

    def update_exercise_progress(self, user_id, exercise_id, progress):
        user_exercise_progress = User_Exercise_Progress(user_id, exercise_id, progress)
        self.user_exercise_progress.append(user_exercise_progress)

class FeedGenerationService:
    def __init__(self):
        self.feed_items = []

    def generate_feed(self, user_id):
        # Simulating feed generation based on progress and interests
        # Replace the following code with the actual implementation
        feed_items = []
        for i in range(10):
            feed_item = {
                'user_id': user_id,
                'post_id': i,
                'caption': f'Post {i} caption',
                'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S')
            }
            feed_items.append(feed_item)
        self.feed_items.extend(feed_items)

    def get_user_feed(self, user_id):
        user_feed = []
        for feed_item in self.feed_items:
            if feed_item['user_id'] == user_id:
                user_feed.append(feed_item)
        return user_feed

# Example usage
course_service = CourseService()
course_service.create_course(1, "English Course", "Learn English", "Beginner")

lesson_service = LessonService()
lesson_service.create_lesson(1, 1, "Lesson 1")

exercise_service = ExerciseService()
exercise_service.create_exercise(1, 1, "Exercise 1")

user_service = UserService()
user_service.register_user(1, "JohnDoe", "[email protected]", "password")

progress_service = ProgressTrackingService()
progress_service.update_course_progress(1, 1, 50)
progress_service.update_lesson_progress(1, 1, 75)
progress_service.update_exercise_progress(1, 1, 100)

feed_service = FeedGenerationService()
feed_service.generate_feed(1)
user_feed = feed_service.get_user_feed(1)

print(course_service.get_course_details(1).name)   # Output: English Course
print(user_service.get_user_profile(1).username)   # Output: JohnDoe
print(user_feed)                                   # Output: [{'user_id': 1, 'post_id': 0, 'caption': 'Post 0 caption', 'timestamp': '2023-07-08 14:30:00'}, ...]

class User:
    def __init__(self, userId, username, password, email):
        self.userId = userId
        self.username = username
        self.password = password
        self.email = email
        # Additional attributes for the user
    
    # Getters and setters for the attributes

class Course:
    def __init__(self, courseId, name, description, difficultyLevel):
        self.courseId = courseId
        self.name = name
        self.description = description
        self.difficultyLevel = difficultyLevel
        # Additional attributes for the course
    
    # Getters and setters for the attributes

class Lesson:
    def __init__(self, lessonId, courseId, name):
        self.lessonId = lessonId
        self.courseId = courseId
        self.name = name
        # Additional attributes for the lesson
    
    # Getters and setters for the attributes

class Exercise:
    def __init__(self, exerciseId, lessonId, name):
        self.exerciseId = exerciseId
        self.lessonId = lessonId
        self.name = name
        # Additional attributes for the exercise
    
    # Getters and setters for the attributes

class UserCourseProgress:
    def __init__(self, userId, courseId, progress):
        self.userId = userId
        self.courseId = courseId
        self.progress = progress
        # Additional attributes for user-course progress
    
    # Getters and setters for the attributes

class UserLessonProgress:
    def __init__(self, userId, lessonId, progress):
        self.userId = userId
        self.lessonId = lessonId
        self.progress = progress
        # Additional attributes for user-lesson progress
    
    # Getters and setters for the attributes

class UserExerciseProgress:
    def __init__(self, userId, exerciseId, progress):
        self.userId = userId
        self.exerciseId = exerciseId
        self.progress = progress
        # Additional attributes for user-exercise progress
    
    # Getters and setters for the attributes

# Example usage
user1 = User(1, "JohnDoe", "password123", "[email protected]")
course1 = Course(1, "English Course", "Learn English", "Beginner")
lesson1 = Lesson(1, 1, "Lesson 1")
exercise1 = Exercise(1, 1, "Exercise 1")
user_course_progress1 = UserCourseProgress(1, 1, 50)
user_lesson_progress1 = UserLessonProgress(1, 1, 75)
user_exercise_progress1 = UserExerciseProgress(1, 1, 100)

# Accessing attributes
print(user1.username)                       # Output: JohnDoe
print(course1.name)                         # Output: English Course
print(lesson1.name)                         # Output: Lesson 1
print(exercise1.name)                       # Output: Exercise 1
print(user_course_progress1.progress)       # Output: 50
print(user_lesson_progress1.progress)       # Output: 75
print(user_exercise_progress1.progress)     # Output: 100

from flask import Flask, jsonify, request

app = Flask(__name__)

@app.route('/users/<user_id>', methods=['GET'])
def get_user_profile(user_id):
    # Fetch user profile from the database based on the user_id
    # Replace the following code with actual implementation
    user_profile = {
        "user_id": user_id,
        "name": "John Doe",
        "email": "[email protected]",
        "language_preferences": ["English", "Spanish"],
        "learning_progress": {
            "course_id": "456",
            "lesson_id": "789",
            "exercise_id": "987"
        }
    }
    return jsonify(user_profile)

@app.route('/users/<user_id>/courses/<course_id>', methods=['POST'])
def enroll_user_in_course(user_id, course_id):
    # Access request data from the request body
    enrollment_date = request.json.get('enrollment_date')

    # Enroll the user in the course based on user_id and course_id
    # Replace the following code with actual implementation
    enrollment_data = {
        "user_id": user_id,
        "course_id": course_id,
        "enrollment_date": enrollment_date
    }
    return jsonify(enrollment_data), 201

@app.route('/users/<user_id>/lessons/<lesson_id>/progress', methods=['POST'])
def update_lesson_progress(user_id, lesson_id):
    # Access request data from the request body
    progress = request.json.get('progress')

    # Update user progress for the lesson based on user_id and lesson_id
    # Replace the following code with actual implementation
    progress_data = {
        "user_id": user_id,
        "lesson_id": lesson_id,
        "progress": progress
    }
    return jsonify(progress_data), 200

@app.route('/users/<user_id>/exercises/<exercise_id>/submit', methods=['POST'])
def submit_exercise_response(user_id, exercise_id):
    # Access request data from the request body
    user_response = request.json.get('user_response')

    # Process user's response for the exercise based on user_id and exercise_id
    # Replace the following code with actual implementation
    response_data = {
        "user_id": user_id,
        "exercise_id": exercise_id,
        "user_response": user_response
    }
    return jsonify(response_data), 200

if __name__ == '__main__':
    app.run(debug=True)

class Course:
    def __init__(self, course_id, name, lessons):
        self.course_id = course_id
        self.name = name
        self.lessons = lessons

class Lesson:
    def __init__(self, lesson_id, name, exercises):
        self.lesson_id = lesson_id
        self.name = name
        self.exercises = exercises

class Exercise:
    def __init__(self, exercise_id, name):
        self.exercise_id = exercise_id
        self.name = name

# Creating a sample course
exercise1 = Exercise(1, "Exercise 1")
exercise2 = Exercise(2, "Exercise 2")
lesson = Lesson(1, "Lesson 1", [exercise1, exercise2])
course = Course(1, "Spanish Course", [lesson])

print(course.name)           # Output: Spanish Course
print(course.lessons[0].name) # Output: Lesson 1

class User:
    def __init__(self, user_id, name):
        self.user_id = user_id
        self.name = name
        self.streak = 0
        self.achievements = []
        self.leaderboard_rank = None

    def increase_streak(self):
        self.streak += 1

    def add_achievement(self, achievement):
        self.achievements.append(achievement)

    def set_leaderboard_rank(self, rank):
        self.leaderboard_rank = rank

# Creating a sample user and demonstrating gamification features
user = User(1, "John Doe")
user.increase_streak()
user.add_achievement("Completed Lesson 1")
user.set_leaderboard_rank(5)

print(user.streak)                     # Output: 1
print(user.achievements)                # Output: ['Completed Lesson 1']
print(user.leaderboard_rank)            # Output: 5

class LearningAlgorithm:
    def __init__(self):
        # Initialize the learning algorithm

    def personalize_learning(self, user):
        # Implement the logic to personalize learning experience based on user performance and progress
        # Replace the following code with the actual implementation
        if user.streak > 10:
            print("Congratulations! You have a long streak. Let's challenge you with more advanced exercises.")
        else:
            print("Keep up the good work! Let's continue with the next lesson.")

# Creating a learning algorithm and personalizing learning for a user
algorithm = LearningAlgorithm()
algorithm.personalize_learning(user)

class CourseContent:
    def __init__(self, course_id, lessons):
        self.course_id = course_id
        self.lessons = lessons

    def add_lesson(self, lesson):
        self.lessons.append(lesson)

# Creating a sample course content and adding a lesson through crowdsourcing
content = CourseContent(1, [])
lesson = Lesson(2, "Lesson 2", [])
content.add_lesson(lesson)

print(content.lessons[0].name)  # Output: Lesson 2

class MobileApp:
    def __init__(self, platform):
        self.platform = platform

    def learn_on_the_go(self):
        # Implement the logic to enable learning on the go for the specific mobile platform
        # Replace the following code with the actual implementation
        print(f"Learning on the go with {self.platform} app!")

# Creating mobile apps for iOS and Android
ios_app = MobileApp("iOS")
android_app = MobileApp("Android")
ios_app.learn_on_the_go()       # Output: Learning on the go with iOS app!
android_app.learn_on_the_go()   # Output: Learning on the go with Android app!

class User:
    def __init__(self, username, password, email):
        self.username = username
        self.password = password
        self.email = email

class UserService:
    def __init__(self):
        self.users = []

    def register_user(self, username, password, email):
        new_user = User(username, password, email)
        self.users.append(new_user)
        return new_user

    def authenticate_user(self, username, password):
        for user in self.users:
            if user.username == username and user.password == password:
                return user
        return None

    def update_profile(self, user, profile_data):
        # Logic to update user profile
        # ...
        pass


class Restaurant:
    def __init__(self, name, cuisine_type):
        self.name = name
        self.cuisine_type = cuisine_type

class RestaurantService:
    def __init__(self):
        self.restaurants = []

    def add_restaurant(self, name, cuisine_type):
        new_restaurant = Restaurant(name, cuisine_type)
        self.restaurants.append(new_restaurant)
        return new_restaurant

    def update_restaurant(self, restaurant, update_data):
        # Logic to update restaurant details
        # ...
        pass

    def get_restaurant(self, restaurant_id):
        for restaurant in self.restaurants:
            if restaurant.id == restaurant_id:
                return restaurant
        return None


class MenuItem:
    def __init__(self, name, price):
        self.name = name
        self.price = price

class MenuService:
    def __init__(self):
        self.menus = {}

    def add_menu_item(self, restaurant_id, item_name, item_price):
        new_item = MenuItem(item_name, item_price)
        if restaurant_id in self.menus:
            self.menus[restaurant_id].append(new_item)
        else:
            self.menus[restaurant_id] = [new_item]
        return new_item

    def update_menu_item(self, item, update_data):
        # Logic to update a menu item
        # ...
        pass

    def get_menu_items(self, restaurant_id):
        if restaurant_id in self.menus:
            return self.menus[restaurant_id]
        return []


class Order:
    def __init__(self, user, restaurant, items):
        self.user = user
        self.restaurant = restaurant
        self.items = items
        self.status = "Placed"

class OrderService:
    def __init__(self):
        self.orders = []
        self.order_id_counter = 1

    def place_order(self, user, restaurant, items):
        new_order = Order(user, restaurant, items)
        new_order.order_id = self.order_id_counter
        self.order_id_counter += 1
        self.orders.append(new_order)
        return new_order

    def process_order(self, order):
        # Logic to process an order
        # ...
        pass

    def update_order_status(self, order, status):
        order.status = status


class PaymentService:
    def process_payment(self, user, order, payment_details):
        # Logic to process a payment
        # ...
        pass

    def get_transaction_details(self, transaction_id):
        # Logic to retrieve transaction details
        # ...
        pass


class RatingService:
    def __init__(self):
        self.ratings = {}

    def rate_restaurant(self, user, restaurant, rating):
        if restaurant.id in self.ratings:
            self.ratings[restaurant.id].append((user.id, rating))
        else:
            self.ratings[restaurant.id] = [(user.id, rating)]

    def get_restaurant_rating(self, restaurant):
        if restaurant.id in self.ratings:
            ratings = self.ratings[restaurant.id]
            average_rating = sum(rating for _, rating in ratings) / len(ratings)
            return average_rating
        return None

    def get_user_rating(self, user, restaurant):
        if restaurant.id in self.ratings:
            ratings = self.ratings[restaurant.id]
            for user_id, rating in ratings:
                if user_id == user.id:
                    return rating
        return None


class FeedService:
    def generate_personalized_feed(self, user):
        # Logic to generate a personalized feed for a user
        # ...
        pass

class User:
    def __init__(self, user_id, username, password):
        self.user_id = user_id
        self.username = username
        self.password = password
        # Other user attributes

class Restaurant:
    def __init__(self, restaurant_id, name, cuisine_type):
        self.restaurant_id = restaurant_id
        self.name = name
        self.cuisine_type = cuisine_type
        # Other restaurant attributes

class Order:
    def __init__(self, order_id, user_id, restaurant_id, items):
        self.order_id = order_id
        self.user_id = user_id
        self.restaurant_id = restaurant_id
        self.items = items
        # Other order attributes

class FoodPanda:
    def __init__(self):
        self.users = {}
        self.restaurants = {}
        self.orders = []
        # Other data structures for storing users, restaurants, and orders

    def register_user(self, username, password):
        # Logic to register a new user
        pass

    def login_user(self, username, password):
        # Logic to authenticate and login a user
        pass

    def add_restaurant(self, name, cuisine_type):
        # Logic to add a new restaurant
        pass

    def place_order(self, user_id, restaurant_id, items):
        # Logic to place a new order
        pass

    # Other methods for managing users, restaurants, and orders

from flask import Flask, request, jsonify

app = Flask(__name__)

# In-memory storage for simplicity (replace with a proper database in production)
users = {}

@app.route('/users/<user_id>', methods=['GET'])
def get_user(user_id):
    if user_id in users:
        return jsonify(users[user_id])
    else:
        return jsonify({'error': 'User not found'}), 404

@app.route('/users', methods=['POST'])
def create_user():
    user_data = request.get_json()
    user_id = user_data.get('user_id')

    if user_id in users:
        return jsonify({'error': 'User already exists'}), 400

    users[user_id] = user_data
    return jsonify({'message': 'User created successfully'})

@app.route('/users/<user_id>', methods=['PUT'])
def update_user(user_id):
    if user_id in users:
        user_data = request.get_json()
        users[user_id].update(user_data)
        return jsonify({'message': 'User updated successfully'})
    else:
        return jsonify({'error': 'User not found'}), 404

@app.route('/users/<user_id>', methods=['DELETE'])
def delete_user(user_id):
    if user_id in users:
        del users[user_id]
        return jsonify({'message': 'User deleted successfully'})
    else:
        return jsonify({'error': 'User not found'}), 404

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

users = []

@app.route('/register', methods=['POST'])
def register_user():
    user_data = request.get_json()
    users.append(user_data)
    return jsonify({'message': 'User registered successfully'})

@app.route('/login', methods=['POST'])
def login_user():
    user_credentials = request.get_json()
    for user in users:
        if user['email'] == user_credentials['email'] and user['password'] == user_credentials['password']:
            return jsonify({'message': 'Login successful'})
    return jsonify({'error': 'Invalid credentials'}), 401

if __name__ == '__main__':
    app.run()

from flask import Flask, jsonify

app = Flask(__name__)

restaurants = [
    {
        'id': 1,
        'name': 'Pizza Place',
        'cuisine': 'Italian',
        'menu': [
            {'id': 1, 'name': 'Margherita Pizza', 'price': 10.99},
            {'id': 2, 'name': 'Pepperoni Pizza', 'price': 12.99},
            {'id': 3, 'name': 'Vegetarian Pizza', 'price': 11.99},
        ]
    },
    {
        'id': 2,
        'name': 'Sushi House',
        'cuisine': 'Japanese',
        'menu': [
            {'id': 4, 'name': 'California Roll', 'price': 8.99},
            {'id': 5, 'name': 'Salmon Nigiri', 'price': 5.99},
            {'id': 6, 'name': 'Tuna Sashimi', 'price': 7.99},
        ]
    },
]

@app.route('/restaurants', methods=['GET'])
def get_restaurants():
    return jsonify(restaurants)

@app.route('/restaurants/<int:restaurant_id>', methods=['GET'])
def get_restaurant(restaurant_id):
    for restaurant in restaurants:
        if restaurant['id'] == restaurant_id:
            return jsonify(restaurant)
    return jsonify({'error': 'Restaurant not found'}), 404

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

restaurants = [
    # Restaurant data
]

@app.route('/search', methods=['GET'])
def search_restaurants():
    cuisine = request.args.get('cuisine')
    price_range = request.args.get('price_range')
    ratings = request.args.get('ratings')
    # Perform search and filtering based on parameters
    # ...

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

orders = []

@app.route('/place_order', methods=['POST'])
def place_order():
    order_data = request.get_json()
    orders.append(order_data)
    return jsonify({'message': 'Order placed successfully'})

@app.route('/make_payment', methods=['POST'])
def make_payment():
    payment_data = request.get_json()
    # Process payment logic
    # ...

if __name__ == '__main__':
    app.run()

from flask import Flask, jsonify

app = Flask(__name__)

orders = [
    # Order data
]

@app.route('/track_order/<int:order_id>', methods=['GET'])
def track_order(order_id):
    for order in orders:
        if order['id'] == order_id:
            return jsonify(order)
    return jsonify({'error': 'Order not found'}), 404

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

restaurants = [
    # Restaurant data
]

@app.route('/restaurants/<int:restaurant_id>/rate', methods=['POST'])
def rate_restaurant(restaurant_id):
    rating_data = request.get_json()
    for restaurant in restaurants:
        if restaurant['id'] == restaurant_id:
            restaurant.setdefault('ratings', []).append(rating_data)
            return jsonify({'message': 'Rating added successfully'})
    return jsonify({'error': 'Restaurant not found'}), 404

if __name__ == '__main__':
    app.run()

from flask import Flask, jsonify, request

app = Flask(__name__)

# Sample data for demonstration purposes
users = [
    {"user_id": 1, "name": "John Doe", "email": "[email protected]"},
    {"user_id": 2, "name": "Jane Smith", "email": "[email protected]"},
    # ...
]

restaurants = [
    {"restaurant_id": 1, "name": "Pizza Place", "cuisine": "Italian"},
    {"restaurant_id": 2, "name": "Sushi House", "cuisine": "Japanese"},
    # ...
]

orders = [
    {"order_id": 1, "user_id": 1, "restaurant_id": 1, "status": "pending"},
    {"order_id": 2, "user_id": 2, "restaurant_id": 2, "status": "completed"},
    # ...
]

payments = [
    {"payment_id": 1, "order_id": 1, "amount": 25.99},
    {"payment_id": 2, "order_id": 2, "amount": 42.50},
    # ...
]

# User API
@app.route('/users/<int:user_id>', methods=['GET'])
def get_user(user_id):
    user = next((user for user in users if user['user_id'] == user_id), None)
    if user:
        return jsonify(user)
    return jsonify({'error': 'User not found'}), 404

@app.route('/users', methods=['POST'])
def create_user():
    user_data = request.get_json()
    # Perform validation and save user data
    # ...

@app.route('/users/<int:user_id>', methods=['PUT'])
def update_user(user_id):
    user_data = request.get_json()
    # Update user data for user_id
    # ...

@app.route('/users/<int:user_id>', methods=['DELETE'])
def delete_user(user_id):
    # Delete user with user_id
    # ...

# Restaurant API
@app.route('/restaurants', methods=['GET'])
def get_restaurants():
    return jsonify(restaurants)

@app.route('/restaurants/<int:restaurant_id>', methods=['GET'])
def get_restaurant(restaurant_id):
    restaurant = next((restaurant for restaurant in restaurants if restaurant['restaurant_id'] == restaurant_id), None)
    if restaurant:
        return jsonify(restaurant)
    return jsonify({'error': 'Restaurant not found'}), 404

# Order API
@app.route('/orders/<int:order_id>', methods=['GET'])
def get_order(order_id):
    order = next((order for order in orders if order['order_id'] == order_id), None)
    if order:
        return jsonify(order)
    return jsonify({'error': 'Order not found'}), 404

# Payment API
@app.route('/payments/<int:payment_id>', methods=['GET'])
def get_payment(payment_id):
    payment = next((payment for payment in payments if payment['payment_id'] == payment_id), None)
    if payment:
        return jsonify(payment)
    return jsonify({'error': 'Payment not found'}), 404

if __name__ == '__main__':
    app.run()

class LikeService:
    def __init__(self, database):
        self.database = database
    
    def like_song(self, user_id, song_id):
        # Logic to like a song and store the like information in the database
        like_id = self.database.generate_like_id()
        timestamp = self.database.get_current_timestamp()
        self.database.save_like(like_id, user_id, song_id, timestamp)

class CommentService:
    def __init__(self, database):
        self.database = database
    
    def add_comment(self, user_id, song_id, caption):
        # Logic to add a comment to a song and store the comment information in the database
        comment_id = self.database.generate_comment_id()
        timestamp = self.database.get_current_timestamp()
        self.database.save_comment(comment_id, user_id, song_id, caption, timestamp)
    
    def add_reply(self, user_id, song_id, comment_id, reply):
        # Logic to add a reply to a comment and store the reply information in the database
        reply_id = self.database.generate_reply_id()
        timestamp = self.database.get_current_timestamp()
        self.database.save_reply(reply_id, user_id, song_id, comment_id, reply, timestamp)

class FollowService:
    def __init__(self, database):
        self.database = database
    
    def follow_user(self, user_id, target_user_id):
        # Logic to allow a user to follow another user and store the relationship in the database
        self.database.save_follow(user_id, target_user_id)
    
    def unfollow_user(self, user_id, target_user_id):
        # Logic to allow a user to unfollow another user and remove the relationship from the database
        self.database.delete_follow(user_id, target_user_id)

class PlaylistService:
    def __init__(self, database):
        self.database = database
    
    def create_playlist(self, user_id, playlist_name):
        # Logic to create a new playlist for a user and store it in the database
        playlist_id = self.database.generate_playlist_id()
        self.database.save_playlist(playlist_id, user_id, playlist_name)
    
    def add_song_to_playlist(self, user_id, playlist_id, song_id):
        # Logic to add a song to a user's playlist and store the information in the database
        self.database.save_song_to_playlist(user_id, playlist_id, song_id)
    
    def share_playlist(self, user_id, playlist_id, recipients):
        # Logic to share a playlist with other users and notify them
        playlist_name = self.database.get_playlist_name(playlist_id)
        for recipient_id in recipients:
            self.database.save_notification(recipient_id, user_id, playlist_id, playlist_name)

class FeedGenerationService:
    def __init__(self, user_data, song_data):
        self.user_data = user_data
        self.song_data = song_data
    
    def generate_personalized_feed(self, user_id):
        # Retrieve user's listening history and preferences
        user_history = self.user_data.get_listening_history(user_id)
        user_preferences = self.user_data.get_preferences(user_id)
        
        # Fetch songs from followed artists
        followed_artists = self.user_data.get_followed_artists(user_id)
        followed_artists_songs = self.song_data.get_songs_by_artists(followed_artists)
        
        # Combine songs from followed artists with user preferences
        feed_songs = user_history + user_preferences + followed_artists_songs
        
        # Shuffle the songs and select a subset for the feed
        random.shuffle(feed_songs)
        feed_songs = feed_songs[:50]
        
        return feed_songs

import java.util.*;

class User {
    private String userId;
    private String username;
    private String password;
    // other user attributes
    
    public User(String userId, String username, String password) {
        this.userId = userId;
        this.username = username;
        this.password = password;
        // initialize other attributes
    }
    
    // Getters and setters for attributes
    // ...
}

class Song {
    private String songId;
    private String title;
    private String artist;
    private String duration;
    // other song attributes
    
    public Song(String songId, String title, String artist, String duration) {
        this.songId = songId;
        this.title = title;
        this.artist = artist;
        this.duration = duration;
        // initialize other attributes
    }
    
    // Getters and setters for attributes
    // ...
}

class Playlist {
    private String playlistId;
    private String name;
    private User user;
    private List<Song> songs;
    
    public Playlist(String playlistId, String name, User user) {
        this.playlistId = playlistId;
        this.name = name;
        this.user = user;
        this.songs = new ArrayList<>();
    }
    
    // Getters and setters for attributes
    // ...
}

class Saavn {
    private Map<String, User> users;
    private Map<String, Song> songs;
    private Map<String, Playlist> playlists;
    
    public Saavn() {
        this.users = new HashMap<>();
        this.songs = new HashMap<>();
        this.playlists = new HashMap<>();
    }
    
    public void addUser(User user) {
        users.put(user.getUserId(), user);
    }
    
    public User getUserById(String userId) {
        return users.get(userId);
    }
    
    public void addSong(Song song) {
        songs.put(song.getSongId(), song);
    }
    
    public Song getSongById(String songId) {
        return songs.get(songId);
    }
    
    public void createPlaylist(String playlistId, String name, String userId) {
        User user = getUserById(userId);
        
        if (user == null) {
            System.out.println("User not found");
            return;
        }
        
        Playlist playlist = new Playlist(playlistId, name, user);
        playlists.put(playlistId, playlist);
        
        // Additional logic to update user's playlists, etc.
        // ...
    }
    
    public void addSongToPlaylist(String playlistId, String songId) {
        Playlist playlist = playlists.get(playlistId);
        Song song = songs.get(songId);
        
        if (playlist == null || song == null) {
            System.out.println("Playlist or song not found");
            return;
        }
        
        playlist.getSongs().add(song);
    }
    
    // Additional methods for handling user authentication, song search, etc.
    // ...
}

public class Main {
    public static void main(String[] args) {
        Saavn saavn = new Saavn();
        
        User user1 = new User("1", "Alice", "password");
        User user2 = new User("2", "Bob", "password");
        
        saavn.addUser(user1);
        saavn.addUser(user2);
        
        Song song1 = new Song("1", "Song 1", "Artist 1", "3:30");
        Song song2 = new Song("2", "Song 2", "Artist 2", "4:15");
        
        saavn.addSong(song1);
        saavn.addSong(song2);
        
        saavn.createPlaylist("1", "My Playlist", "1");
        
        saavn.addSongToPlaylist("1", "1");
    }
}

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/api/authenticate', methods=['POST'])
def authenticate_user():
    username = request.json['username']
    password = request.json['password']
    
    # Perform authentication logic, validate credentials, and generate access token
    
    access_token = generate_access_token(username)
    
    response = {
        "access_token": access_token,
        "token_type": "bearer",
        "expires_in": 3600
    }
    
    return jsonify(response), 200

if __name__ == '__main__':
    app.run()

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/api/songs/<song_id>', methods=['GET'])
def get_song(song_id):
    # Retrieve song details from the database based on song_id
    
    song = {
        "id": song_id,
        "title": "Song Title",
        "artist": "Artist Name",
        "genre": "Genre",
        "duration": "00:04:30",
        "release_year": 2023
        # additional song details...
    }
    
    return jsonify(song), 200

if __name__ == '__main__':
    app.run()

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/api/playlists', methods=['GET'])
def get_playlists():
    # Retrieve playlists associated with the authenticated user from the database
    
    playlists = [
        {
            "id": "playlist_id",
            "name": "My Playlist",
            "description": "Playlist description",
            "songs_count": 10
            # additional playlist details...
        },
        # additional playlists...
    ]
    
    return jsonify(playlists), 200

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/api/users/<user_id>/follow', methods=['POST'])
def follow_user(user_id):
    followed_user_id = request.json['user_id']
    
    # Perform logic to establish a follow relationship between the authenticated user and followed_user_id
    
    response = {
        "message": f"You are now following the user with ID {followed_user_id}."
    }
    
    return jsonify(response), 200

if __name__ == '__main__':
    app.run()

class SaavnMusicLibrary:
    def __init__(self):
        self.songs = []
        self.albums = []
        self.playlists = []
    
    def add_song(self, song):
        self.songs.append(song)
    
    def add_album(self, album):
        self.albums.append(album)
    
    def add_playlist(self, playlist):
        self.playlists.append(playlist)

class RecommendationEngine:
    def __init__(self, music_library):
        self.music_library = music_library
    
    def generate_personalized_recommendations(self, user):
        # Recommendation logic based on user's listening history and preferences
        # Returns a list of recommended songs
        
        # Example implementation: return a random selection of songs from the library
        import random
        return random.choices(self.music_library.songs, k=5)

class Playlist:
    def __init__(self, name, user):
        self.name = name
        self.user = user
        self.songs = []
    
    def add_song(self, song):
        self.songs.append(song)
    
    def share_playlist(self, friends):
        # Share playlist with friends
        for friend in friends:
            friend.receive_shared_playlist(self)
    
class User:
    def __init__(self, name):
        self.name = name
    
    def create_playlist(self, name):
        playlist = Playlist(name, self)
        return playlist
    
    def receive_shared_playlist(self, playlist):
        # Logic to receive and handle a shared playlist
        print(f"{self.name} received a shared playlist: {playlist.name}")

class Saavn:
    def __init__(self, music_library):
        self.music_library = music_library
        self.downloaded_songs = []
    
    def download_song(self, song):
        # Logic to download a song for offline listening
        self.downloaded_songs.append(song)
    
    def play_song(self, song):
        if song in self.downloaded_songs:
            # Logic to play the downloaded song
            print(f"Now playing: {song.title}")
        else:
            # Logic to handle streaming the song online
            print(f"Now streaming: {song.title}")

class User:
    def __init__(self, name):
        self.name = name
        self.friends = []
    
    def add_friend(self, friend):
        self.friends.append(friend)
    
    def follow_artist(self, artist):
        # Logic to follow an artist
        artist.add_follower(self)
    
class Artist:
    def __init__(self, name):
        self.name = name
        self.followers = []
    
    def add_follower(self, follower):
        self.followers.append(follower)
    
    def notify_followers(self, song):
        # Logic to notify followers about a new song release or activity
        for follower in self.followers:
            follower.receive_notification(song)
    
    def receive_notification(self, song):
        # Logic to handle receiving a notification about an artist's activity
        print(f"{self.name} released a new song: {song.title}")

class WebApplication:
    def __init__(self, saavn):
        self.saavn = saavn
    
    def play_song(self, song):
        self.saavn.play_song(song)
        # Logic specific to the web platform
    
class MobileApplication:
    def __init__(self, saavn):
        self.saavn = saavn
    
    def play_song(self, song):
        self.saavn.play_song(song)
        # Logic specific to the mobile platform
    
class DesktopApplication:
    def __init__(self, saavn):
        self.saavn = saavn
    
    def play_song(self, song):
        self.saavn.play_song(song)

# Import necessary libraries
from flask import Flask, request, jsonify

# Create Flask application
app = Flask(__name__)

# Define route for user authentication
@app.route('/api/authenticate', methods=['POST'])
def authenticate_user():
    # Authentication logic
    username = request.json['username']
    password = request.json['password']
    
    # Perform authentication logic, validate credentials, and generate access token
    access_token = generate_access_token(username)
    
    response = {
        "access_token": access_token,
        "token_type": "bearer",
        "expires_in": 3600
    }
    
    return jsonify(response), 200

# Define route for music retrieval
@app.route('/api/songs/<song_id>', methods=['GET'])
def get_song(song_id):
    # Retrieve song details from the database based on song_id
    song = retrieve_song(song_id)
    
    return jsonify(song), 200

# Define route for playlist management
@app.route('/api/playlists', methods=['GET'])
def get_playlists():
    # Retrieve playlists associated with the authenticated user from the database
    playlists = retrieve_user_playlists()
    
    return jsonify(playlists), 200

# Define route for social interactions
@app.route('/api/users/<user_id>/follow', methods=['POST'])
def follow_user(user_id):
    followed_user_id = request.json['user_id']
    
    # Perform logic to establish a follow relationship between the authenticated user and followed_user_id
    
    response = {
        "message": f"You are now following the user with ID {followed_user_id}."
    }
    
    return jsonify(response), 200

# Main entry point of the application
if __name__ == '__main__':
    app.run()

import java.util.*;
import com.google.gson.Gson;

import spark.Spark;
import spark.Request;
import spark.Response;

class User {
    private String userId;
    private String username;
    private String password;
    // other user attributes

    public User(String userId, String username, String password) {
        this.userId = userId;
        this.username = username;
        this.password = password;
        // initialize other attributes
    }

    // Getters and setters for attributes
    // ...
}

class Song {
    private String songId;
    private String title;
    private String artist;
    private String duration;
    // other song attributes

    public Song(String songId, String title, String artist, String duration) {
        this.songId = songId;
        this.title = title;
        this.artist = artist;
        this.duration = duration;
        // initialize other attributes
    }

    // Getters and setters for attributes
    // ...
}

class Playlist {
    private String playlistId;
    private String name;
    private User user;
    private List<Song> songs;

    public Playlist(String playlistId, String name, User user) {
        this.playlistId = playlistId;
        this.name = name;
        this.user = user;
        this.songs = new ArrayList<>();
    }

    // Getters and setters for attributes
    // ...
}

class Saavn {
    private Map<String, User> users;
    private Map<String, Song> songs;
    private Map<String, Playlist> playlists;

    public Saavn() {
        this.users = new HashMap<>();
        this.songs = new HashMap<>();
        this.playlists = new HashMap<>();
    }

    public void addUser(User user) {
        users.put(user.getUserId(), user);
    }

    public User getUserById(String userId) {
        return users.get(userId);
    }

    public void addSong(Song song) {
        songs.put(song.getSongId(), song);
    }

    public Song getSongById(String songId) {
        return songs.get(songId);
    }

    public void createPlaylist(String playlistId, String name, String userId) {
        User user = getUserById(userId);

        if (user == null) {
            System.out.println("User not found");
            return;
        }

        Playlist playlist = new Playlist(playlistId, name, user);
        playlists.put(playlistId, playlist);

        // Additional logic to update user's playlists, etc.
        // ...
    }

    public void addSongToPlaylist(String playlistId, String songId) {
        Playlist playlist = playlists.get(playlistId);
        Song song = songs.get(songId);

        if (playlist == null || song == null) {
            System.out.println("Playlist or song not found");
            return;
        }

        playlist.getSongs().add(song);
    }

    // Additional methods for handling user authentication, song search, etc.
    // ...
}

public class Main {
    private static Saavn saavn = new Saavn();
    private static Gson gson = new Gson();

    public static void main(String[] args) {
        // Set up Spark server
        Spark.port(8080);

        // User Management API
        Spark.post("/users", Main::createUser);
        Spark.post("/login", Main::loginUser);
        Spark.patch("/users/:userId", Main::updateUser);
        Spark.get("/users/:userId", Main::getUser);

        // Song Management API
        Spark.post("/songs", Main::uploadSong);
        Spark.get("/songs/:songId", Main::getSong);

        // Playlist Management API
        Spark.post("/playlists", Main::createPlaylist);
        Spark.get("/playlists/:playlistId", Main::getPlaylist);
        Spark.patch("/playlists/:playlistId/songs", Main::addSongToPlaylist);

        // Additional API endpoints...

        // Start the Spark server
        Spark.awaitInitialization();
    }

    // User Management API
    private static String createUser(Request request, Response response) {
        User user = gson.fromJson(request.body(), User.class);
        saavn.addUser(user);
        response.status(201);
        return "User created successfully";
    }

    private static String loginUser(Request request, Response response) {
        // Implement login logic here
        return "Login successful";
    }

    private static String updateUser(Request request, Response response) {
        String userId = request.params("userId");
        User user = saavn.getUserById(userId);

        if (user == null) {
            response.status(404);
            return "User not found";
        }

        // Update user profile logic here

        return "Profile updated successfully";
    }

    private static String getUser(Request request, Response response) {
        String userId = request.params("userId");
        User user = saavn.getUserById(userId);

        if (user == null) {
            response.status(404);
            return "User not found";
        }

        return gson.toJson(user);
    }

    // Song Management API
    private static String uploadSong(Request request, Response response) {
        Song song = gson.fromJson(request.body(), Song.class);
        saavn.addSong(song);
        response.status(201);
        return "Song uploaded successfully";
    }

    private static String getSong(Request request, Response response) {
        String songId = request.params("songId");
        Song song = saavn.getSongById(songId);

        if (song == null) {
            response.status(404);
            return "Song not found";
        }

        return gson.toJson(song);
    }

    // Playlist Management API
    private static String createPlaylist(Request request, Response response) {
        // Implement playlist creation logic here
        return "Playlist created successfully";
    }

    private static String getPlaylist(Request request, Response response) {
        // Implement playlist retrieval logic here
        return "Playlist retrieved successfully";
    }

    private static String addSongToPlaylist(Request request, Response response) {
        // Implement adding a song to a playlist logic here
        return "Song added to playlist successfully";
    }

    // Additional API endpoint handlers...

    // Stop the Spark server
    public static void stop() {
        Spark.stop();
        Spark.awaitStop();
    }
}

class User:
    def __init__(self, user_id, username, password):
        self.user_id = user_id
        self.username = username
        self.password = password
        # Additional user attributes

class CodingChallenge:
    def __init__(self, challenge_id, problem_statement, constraints, difficulty):
        self.challenge_id = challenge_id
        self.problem_statement = problem_statement
        self.constraints = constraints
        self.difficulty = difficulty
        # Additional challenge attributes

class Follow:
    def __init__(self, user_id1, user_id2):
        self.user_id1 = user_id1
        self.user_id2 = user_id2

class Post:
    def __init__(self, post_id, user_id, photo_url, caption, timestamp, location):
        self.post_id = post_id
        self.user_id = user_id
        self.photo_url = photo_url
        self.caption = caption
        self.timestamp = timestamp
        self.location = location
        # Additional post attributes

class Like:
    def __init__(self, like_id, user_id, post_id, timestamp):
        self.like_id = like_id
        self.user_id = user_id
        self.post_id = post_id
        self.timestamp = timestamp

class Comment:
    def __init__(self, comment_id, post_id, user_id, caption_text, timestamp):
        self.comment_id = comment_id
        self.post_id = post_id
        self.user_id = user_id
        self.caption_text = caption_text
        self.timestamp = timestamp

class Hackerrank:
    def __init__(self):
        self.users = {}
        self.challenges = []
        self.follows = []
        self.posts = []
        self.likes = []
        self.comments = []
        # Additional data structures for efficient data retrieval and manipulation

    def add_user(self, user):
        self.users[user.user_id] = user

    def get_user_by_id(self, user_id):
        return self.users.get(user_id)

    def create_post(self, user_id, photo_url, caption, location):
        user = self.get_user_by_id(user_id)
        
        if user is None:
            print("User not found")
            return
        
        post_id = generate_unique_post_id()
        timestamp = get_current_timestamp()
        post = Post(post_id, user_id, photo_url, caption, timestamp, location)
        self.posts.append(post)

        # Additional logic for updating user's feed, notifying followers, etc.

    def get_user_feed(self, user_id):
        user_feed = []
        
        for post in self.posts:
            if post.user_id == user_id:
                user_feed.append(post)
        
        return user_feed

    # Additional methods for handling likes, comments, follows, etc.

from flask import Flask, request, jsonify

app = Flask(__name__)
hackerrank = Hackerrank()

@app.route("/users", methods=["POST"])
def create_user():
    data = request.get_json()
    user_id = data["user_id"]
    username = data["username"]
    password = data["password"]
    user = User(user_id, username, password)
    hackerrank.add_user(user)
    return jsonify(message="User created successfully"), 201

@app.route("/users/<user_id>", methods=["GET"])
def get_user(user_id):
    user = hackerrank.get_user_by_id(user_id)
    if user:
        return jsonify(user), 200
    else:
        return jsonify(message="User not found"), 404

@app.route("/challenges", methods=["POST"])
def create_challenge():
    data = request.get_json()
    challenge_id = data["challenge_id"]
    problem_statement = data["problem_statement"]
    constraints = data["constraints"]
    difficulty = data["difficulty"]
    challenge = CodingChallenge(challenge_id, problem_statement, constraints, difficulty)
    hackerrank.challenges.append(challenge)
    return jsonify(message="Challenge created successfully"), 201

@app.route("/challenges/<challenge_id>", methods=["GET"])
def get_challenge(challenge_id):
    for challenge in hackerrank.challenges:
        if challenge.challenge_id == challenge_id:
            return jsonify(challenge), 200
    return jsonify(message="Challenge not found"), 404

@app.route("/challenges", methods=["GET"])
def get_all_challenges():
    return jsonify(hackerrank.challenges), 200

# Additional API endpoints for follows, posts, likes, comments, etc.

if __name__ == "__main__":
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/api/users/register', methods=['POST'])
def register_user():
    username = request.json.get('username')
    email = request.json.get('email')
    password = request.json.get('password')

    # Code to register the user and store details in the database
    # ...

    return jsonify({'message': 'User registered successfully'})

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/api/challenges/submit', methods=['POST'])
def submit_challenge():
    user_id = request.json.get('user_id')
    challenge_id = request.json.get('challenge_id')
    code = request.json.get('code')

    # Code to validate the submission, evaluate the code, and store the result
    # ...

    return jsonify({'message': 'Challenge submitted successfully'})

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/api/users/register', methods=['POST'])
def register_user():
    username = request.json.get('username')
    email = request.json.get('email')
    password = request.json.get('password')

    # Code to validate the inputs, create a new user object, and store it in the database
    # ...

    return jsonify({'message': 'User registered successfully'})

if __name__ == '__main__':
    app.run()

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/api/challenges/submit', methods=['POST'])
def submit_challenge():
    user_id = request.json.get('user_id')
    challenge_id = request.json.get('challenge_id')
    code = request.json.get('code')

    # Code to validate the inputs, fetch the challenge details, evaluate the code, and store the result
    # ...

    return jsonify({'message': 'Challenge submitted successfully'})

if __name__ == '__main__':
    app.run()

class CodingChallenge:
    def __init__(self, challenge_id, problem_statement, constraints, difficulty):
        self.challenge_id = challenge_id
        self.problem_statement = problem_statement
        self.constraints = constraints
        self.difficulty = difficulty

    def evaluate_solution(self, user_solution):
        # Code to evaluate the user's solution and return the result
        # ...
        # Assume the solution is evaluated and a boolean result is returned
        return True

class Contest:
    def __init__(self, contest_id, contest_name, start_time, end_time):
        self.contest_id = contest_id
        self.contest_name = contest_name
        self.start_time = start_time
        self.end_time = end_time
        self.participants = []

    def add_participant(self, user_id):
        self.participants.append(user_id)

    def update_leaderboard(self):
        # Code to update the contest leaderboard based on participant scores
        # ...
        # Assume the leaderboard is updated
        pass

class Certification:
    def __init__(self, certification_id, certification_name, domain):
        self.certification_id = certification_id
        self.certification_name = certification_name
        self.domain = domain

    def get_certification_status(self, user_id):
        # Code to fetch the certification status for a user
        # ...
        # Assume the certification status is retrieved
        return "Certified"

class InterviewPreparation:
    def __init__(self, interview_questions, mock_interviews):
        self.interview_questions = interview_questions
        self.mock_interviews = mock_interviews

    def get_random_question(self):
        # Code to retrieve a random interview question
        # ...
        # Assume a random interview question is selected and returned
        return "Tell me about yourself."

    def schedule_mock_interview(self, user_id):
        # Code to schedule a mock interview for a user
        # ...
        # Assume the mock interview is scheduled
        pass