Coding: Converting Roman Numerals to Integers in JavaScript- LeetCode(13)

In this article, we will be discussing a piece of code that is designed to convert roman values into integers.

The code is a JavaScript function named “romanToInt” that takes a string argument “s”, which represents a Roman numeral. The function converts the Roman numeral to an integer and returns the result.

The function starts by defining an object “map” that maps each Roman numeral symbol to its corresponding integer value. For example, “I” maps to 1, “V” maps to 5, and so on.

Next, the function declares a variable “result” and initializes it to 0. This variable will be used to store the final integer result.

The function then uses a for loop to iterate over each character in the input string “s”. For each character, the function looks up its corresponding integer value in the “map” object.

If the current character is not the last character in the string, the function checks the value of the next character. If the next character has a higher value than the current character, the function adds the difference between the two values to the “result” variable. This is because Roman numeral symbols can be combined to represent larger values, such as “IV” (4) or “IX” (9).

Finally, the function returns the final “result” value, which represents the integer equivalent of the input Roman numeral.

For example, if we call “romanToInt(“XXI”)”, the function would return 21.

Here’s a code snippet that explains the function “romanToInt” in a step-by-step manner:

function romanToInt(s) {
  const map = {
    I: 1,
    V: 5,
    X: 10,
    L: 50,
    C: 100,
    D: 500,
    M: 1000
  };
  let result = 0;
  for (let i = 0; i < s.length; i++) {
    let value = map[s[i]]; // Look up the integer value of the current character
    console.log(`${s[i]} maps to ${value}`);
    if (i + 1 < s.length) {
      let nextValue = map[s[i + 1]];
      console.log(`Next character ${s[i+1]} maps to ${nextValue}`);
      if (nextValue > value) {
        value = nextValue - value; // Calculate the combined value of two symbols
        console.log(`Combined value of ${s[i]} and ${s[i+1]} is ${value}`);
        i++;
      }
    }
    result += value; // Add the current value to the final result
    console.log(`Result so far: ${result}`);
  }
  return result;
}

The code above includes console log statements that show the intermediate values at each step of the conversion process. These log statements help to understand what the code is doing and how the final result is being calculated.

For example, if we call “romanToInt(“XXI”)”, the console output would look like this:

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