LeetCode 389 Find The Difference - Easy

389. Find The Difference — Easy

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Problem

389. Find the Difference -- Easy

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"

Example 3: Input: s = "a", t = "aa" Output: "a"

Example 4: Input: s = "ae", t = "aea" Output: "a"

Constraints: 0 <= s.length <= 1000 t.length == s.length + 1 s and t consist of lower-case English letters.

Solution

class Solution:
    def findTheDifference(self, s: str, t: str) -> str:
        # Initialize ch with 0, because 0 ^ X = X
        # 0 when XORed with any bit would not change the bits value.
        ch = 0
        # XOR all the characters of both s and t.
        for char_ in s:
            ch ^= ord(char_)
        for char_ in t:
            ch ^= ord(char_)
        # What is left after XORing everything is the difference.
        return chr(ch)