0389-find-the-difference.js

// 389. Find the Difference
// Easy   50%


// 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 = function(s, t) {
  const hash = {}
  for (let c of s) hash[c] = (hash[c] || 0) + 1
  for (let c of t) {
    if (!hash[c]) return c
    hash[c]--
  }
  return ''
}

;[
  ['abcd', 'abcde'],            // 'e'
].forEach(args => {
  console.log(findTheDifference(...args))
})

// Solution:
// 用哈希表保存 s 字符串中的字符及其个数。
// 再遍历 t 字符串，若遍历到某个字符不存在哈希表中或在哈希表中的值为0，则返回字符。

// Submission Result: Accepted