LeetCode No.389 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.

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这道题目的大意是：字符串s只含有小写字母，字符串t是由字符串s增加一个字母后重新乱排得到，求增加的字母。

这道题做法很多，我用一个大小为26的数组对应26个字母，即'a'对应arr[0]，'b'对应arr[1]……然后遍历s和t中的字母，在s中就减，在t中就加，最后数组中哪个值不为0（就是为1）对应的字母就是我们要求的字母。

class Solution {public:    char findTheDifference(string s, string t) {        int n = s.size() , arr[26];        memset ( arr , 0 , sizeof ( arr ) );        for ( int i = 0 ; i < n ; i ++ )        {            arr[s[i]-'a'] --;            arr[t[i]-'a'] ++;        }        arr[t[n]-'a'] ++;        for ( int i = 0 ; i < 26 ; i ++ )            if ( arr[i] )                return i + 'a' ;        return 'a';    }};

如有错误，求告知改正！