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;
    }
}

JavaScript

/**
 * @param {number[]} nums
 * @return {number}
 */
var singleNumber = function (nums) {
  let res = 0;
  for (let num of nums) {
    res ^= num;
  }
  return res;
};

Go

func singleNumber(nums []int) int {
	res := 0
	for _, v := range nums {
		res ^= v
	}
	return res
}

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