Single Number

描述

Given an array of integers, every element appears twice except for one. Find that single one.

Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

分析

异或，不仅能处理两次的情况，只要出现偶数次，都可以清零。

代码

Python

// Single Number
// 时间复杂度O(n)，空间复杂度O(1)
public class Solution {
    public int singleNumber(int[] nums) {
        int x = 0;
        for (int i : nums) {
            x ^= i;
        }
        return x;
    }
};

Java

// Single Number
// 时间复杂度O(n)，空间复杂度O(1)
class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int x = 0;
        for (int i : nums) {
            x ^= i;
        }
        return x;
    }
};

C++

# Single Number
# 时间复杂度O(n)，空间复杂度O(1)
class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        x = 0
        for i in nums:
            x ^= i
        return x

相关题目

• Single Number II