LeetCode389. Find the Difference

一、题目

You are given two strings s and t.

String t is generated by random shuffling string s and then add one more letter at a random position.

Return the letter that was added to t.

Example 1:

Input: s = “abcd”, t = “abcde”
Output: “e”
Explanation: ‘e’ is the letter that was added.
Example 2:

Input: s = “”, t = “y”
Output: “y”

Constraints:

0 <= s.length <= 1000
t.length == s.length + 1
s and t consist of lowercase English letters.

二、题解

class Solution {
public:
    char findTheDifference(string s, string t) {
        unordered_map<char,int> map1;
        unordered_map<char,int> map2;
        for(auto x:s){
            map1[x]++;
        }
        for(auto x:t){
            map2[x]++;
        }
        for(int i = 0;i < 26;i++){
            if(map1['a' + i] != map2['a' + i]) return 'a' + i;
        }
        return 'a';
    }
};