2 algorithms - Conversion of roman number to integer and integer to roman number

algo-roman-numbers.js

/**
 * @param {string} s
 * @return {number}
 */
var romanToInt = function(s) {
  let result = 0
  const conversion = {
    "I": 1,
    "V": 5,
    "X": 10,
    "L": 50,
    "C": 100,
    "D": 500,
    "M": 1000
  }

  for(let i =s.length-1; i >= 0; i--){
    const curNum = conversion[s.charAt(i)]
    if(i === s.length-1){
      result += curNum
      continue;
    }

    const prevNum = conversion[s.charAt(i+1)]
    if(curNum < prevNum){
      result -= curNum
    } else {
      result +=curNum
    }
  }

  return result
};

/**
 * @param {number} num
 * @return {string}
 */
var intToRoman = function(num) {
  const conversion = {
    1: "I",
    4: "IV",
    5: "V",
    9: "IX",
    10: "X",
    40: "XL",
    50: "L",
    90: "XC",
    100: "C",
    400: "CD",
    500: "D",
    900: "CM",
    1000: "M"
  }
  const options = [1000, 900, 500, 400, 100, 90, 50, 40, 10,9, 5,4, 1]
  let result = ""
  let step = 0
  while(num > 0){
    let curStep = options[step]
    if(curStep > num){
      step++
      continue
    }

    const times = Math.floor(num/curStep);
    result += conversion[curStep].repeat(times)
    num = num - (curStep*times)
    step++
  }
  return result
};