README_EN.md

136. Single Number

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Description

Given a non-empty 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?

Example 1:

Input: [2,2,1]

Output: 1

Example 2:

Input: [4,1,2,1,2]

Output: 4

Solutions

Python3

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        res = 0
        for num in nums:
            res ^= num
        return res

Java

class Solution {
    public int singleNumber(int[] nums) {
        int res = 0;
        for (int num : nums) {
            res ^= num;
        }
        return res;
    }
}

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