389. Find the Difference

Problem

You are given two strings s and t.

String t is generated by random shuffling string s and then add one more letter at a random position.

Return the letter that was added to t.

  Example 1:

Input: s = "abcd", t = "abcde"
Output: "e"
Explanation: 'e' is the letter that was added.

Example 2:

Input: s = "", t = "y"
Output: "y"

  Constraints:

• 0 <= s.length <= 1000

• t.length == s.length + 1

• s and t consist of lowercase English letters.

Solution

class Solution {
    public char findTheDifference(String s, String t) {
        char c = 0;
        for (char cs : s.toCharArray()) {
            c ^= cs;
        }
        for (char ct : t.toCharArray()) {
            c ^= ct;
        }
        return c;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).