389. Find the Difference

Description

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.

Solution

如果把char换成int，是不是立刻想到用异或去做？其实char就是int啊。

Bit operation

class Solution {
    public char findTheDifference(String s, String t) {
        char diff = t.charAt(t.length() - 1);
        for (int i = 0; i < t.length() - 1; ++i) {
            diff ^= s.charAt(i);
            diff ^= t.charAt(i);
        }
        return diff;
    }
}