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.

Solution:

Similar to Single number, XOR all letters in s and t, the letter added will be the only letter appears once.

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

        return (char)xor;
    }