TypeScript

Mister-Hope

/*
 * Runtime: 184 ms, faster than 27.46% of TypeScript online submissions for Roman to Integer.
 *
 * Memory Usage: 45.8 MB, less than 5.18% of TypeScript online submissions for Roman to Integer.
 */

const romanToInt = (s: string): number => {
  let result = 0;
  const map: Record<string, number> = {
    I: 1,
    V: 5,
    X: 10,
    L: 50,
    C: 100,
    D: 500,
    M: 1000,
  };

  for (let i = s.length - 1; i >= 0; i--) {
    let val = map[s.charAt(i)];
    if (i < s.length - 1 && val < map[s.charAt(i + 1)]) val = -val;
    result += val;
  }
  return result;
};