[leetcode] 389. Find the Difference 解题报告

题目链接: https://leetcode.com/problems/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:eExplanation:'e' is the letter that was added.

思路: 一个hash表可以解决, 甚至可以用两个加起来然后异或

代码如下:

class Solution {public:    char findTheDifference(string s, string t) {        unordered_map<char, int> hash;        char ans;        for(auto ch: s) hash[ch]++;        for(auto ch: t)             if(--hash[ch]<0) ans = ch;         return ans;    }};

class Solution {public:    char findTheDifference(string s, string t) {        s += t;        int ch =0;        for(auto val: s) ch ^= val;        return ch;    }};