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.

解题思路为XOR位操作。 由于相同的字符异或之后为0，因此将s和t的每个字符都做异或操作后，最后剩下的即是多出来的那个不同的字符。

public class Solution {
    public char findTheDifference(String s, String t) {
        char c = 0;
        for(int i = 0; i < s.length(); i++) {
            c ^= s.charAt(i);
        }
        for(int i = 0; i < t.length(); i++) {
            c ^= t.charAt(i);
        }
        return c;
    }
}