[LC] 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:

class Solution {
    public char findTheDifference(String s, String t) {
        int res = 0;
        for (char c : s.toCharArray()) {
            res ^= c - 'a'; 
        }
        for (char ch : t.toCharArray()) {
            res ^= ch - 'a';
        }
        return (char)(res + 'a');
    }
}

e

Explanation:
'e' is the letter that was added.