find-the-difference.js

/**
 * Find the Difference
 *
 * Given two strings s and t which consist of only lowercase letters.
 *
 * String t is generated by random shuffling string s and then add one more letter at a random position.
 *
 * Find the letter that was added in t.
 *
 * Example:
 *
 * Input:
 * s = "abcd"
 * t = "abcde"
 *
 * Output:
 * e
 *
 * Explanation:
 * 'e' is the letter that was added.
 */

/**
 * @param {string} s
 * @param {string} t
 * @return {character}
 */
const findTheDifference = (s, t) => {
  let code = t.charCodeAt(t.length - 1);

  for (let i = 0; i < t.length - 1; i++) {
    code ^= s.charCodeAt(i);
    code ^= t.charCodeAt(i);
  }

  return String.fromCharCode(code);
};