https://leetcode.com/problems/roman-to-integer/submissions/

romanToInt.js

// https://leetcode.com/problems/roman-to-integer/submissions/
/**
 * @param {string} s
 * @return {number}
 */
var romanToInt = function(s) {
    const map = new Map();
    map.set('I', 1);
    map.set('V', 5);
    map.set('X', 10);
    map.set('L', 50);
    map.set('C', 100);
    map.set('D', 500);
    map.set('M', 1000);
    let sum = map.get(s[s.length - 1]);
    for (let i = s.length - 1; i >= 1; i--) {
        const last1 = map.get(s[i]);
        const last2 = map.get(s[i-1]);
        if (last2 < last1) {
            sum -= last2;
        } else {
            sum += last2;
        }
        
    }
    return sum;
};