[leetcode]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:
e

Explanation:
'e' is the letter that was added.

分析：

要求找出s和t中不同的字符。首先记录在t中出现的字符，再减去s中相应的字符，剩下的便是多出来的字符了。

class Solution {
public:
    char findTheDifference(string s, string t) {
        char res = 0;
        for(char c : t)
            res += c;
        for(char c : s)
            res -= c;        
        return res;
    }
};