【LeetCode】389. Find the Difference

问题描述

问题链接：https://leetcode.com/problems/find-the-difference/#/description

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.

我的代码

核心思路就是那个找哪个字母只出现了一次的问题里面用的异或。

public class Solution {
    public char findTheDifference(String s, String t) {
        /*
        思路就是用异或，最后生下来的那个转成char
        */
        int mask = 0x0;
        int sLen = s.length();
        int tLen = t.length();
        for(int i = 0; i < sLen; i++){
            mask ^= (int)s.charAt(i);
        }
        for(int i = 0; i < tLen; i++){
            mask ^= (int)t.charAt(i);
        }
        return (char)mask;
    }
}

打败了33.47%的Java代码。来学习一下讨论区。

讨论区

Java solution using bit manipulation

链接地址：https://discuss.leetcode.com/topic/55912/java-solution-using-bit-manipulation/2

这个代码真是优雅。太美了。

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;
}