0136.SingleNumber.js

// 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
//  

// Constraints:

// 1 <= nums.length <= 3 * 104
// -3 * 104 <= nums[i] <= 3 * 104
// Each element in the array appears twice except for one element which appears only once.

// 来源：力扣（LeetCode）
// 链接：https://leetcode-cn.com/problems/single-number
// 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

// 🎨 方法一：位运算

// 📝 思路：利用异或性质 https://leetcode-cn.com/problems/single-number/solution/zhi-chu-xian-yi-ci-de-shu-zi-by-leetcode-solution/

/**
 * @param {number[]} nums
 * @return {number}
 */
var singleNumber = function (nums) {

  let ans = 0;

  for (let num of nums) {
    ans ^= num
  }

  return ans
};