Question:

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:

Java:

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