Find the Difference

妈呀又是神奇的异或……虽然哈希也可以，然而跟异或比起来就不值一提了……

class Solution {public:    char findTheDifference(string s, string t) {         char r=0;         for(auto c:s) r^=c;         for(auto c:t) r^=c;         return r;    }};