LeetCode: 389 Find the Difference(easy)

题目：

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.

代码：

自己的：

 class Solution {
 public:
     char findTheDifference(string s, string t) {
         sort(s.begin(), s.end());
         sort(t.begin(), t.end());
         auto r = mismatch(s.begin(), s.end(), t.begin());
         return (*r.second);
     }
 };

别人的（1）：

 class Solution {
 public:
     char findTheDifference(string s, string t) {
         // Similar to single number. Can do using hashmap...
         int charmap[] = {};
         for(char c: t) {
             charmap[c-'a']++;
         }
         // Iterate over s, one letter will have count 1 left
         for(char c: s) {
             charmap[c-'a']--;
         }
         for(int i=;i<;i++) {
             if (charmap[i] == )
                 return 'a'+i;
         }
         return -;
     }
 };

别人的（2）：

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