leetcode刷题系列-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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class Solution {public:    char findTheDifference(string s, string t) {        int lens = s.size();        int lent = t.size();        map<char,int> s_m;        for(int i = 0; i < lens; ++i)        {            if(s_m.find(s[i]) != s_m.end())                s_m[s[i]]++;            else                s_m[s[i]] = 1;        }        for(int i = 0; i < lent; ++i)        {            if(s_m.find(t[i]) == s_m.end())            {                                return t[i];            }            else            {                s_m[t[i]]--;                if(s_m[t[i]] < 0)                    return t[i];            }        }        return t[0];    }};