389. Find the Difference

389. Find the Difference (Easy)

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.

Related Topics:
Hash Table, Bit Manipulation

Similar Questions:

• Single Number (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/find-the-difference/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    char findTheDifference(string s, string t) {
        int cnt[26] = {};
        for (char c : s) cnt[c - 'a']++;
        for (char c : t) {
            if (--cnt[c - 'a'] < 0) return c;
        }
        return 0;
    }
};