Leetcode•Oct 16, 2025
Single Number
Hazrat Ali
Leetcode
Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.
You must implement a solution with a linear runtime complexity and use only constant extra space.
Example 1:
Input: nums = [2,2,1]
Output: 1
Example 2:
Input: nums = [4,1,2,1,2]
Output: 4
Example 3:
Input: nums = [1]
Output: 1
Solution
/**
* @param {number[]} nums
* @return {number}
*/
var singleNumber = function(nums) {
let result = 0;
for (let num of nums) {
result ^= num;
}
return result;
};
console.log(singleNumber([2, 2, 1]));
console.log(singleNumber([4, 1, 2, 1, 2]));
console.log(singleNumber([1]));