Problem Description

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.

Examples

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.

解析

給定一個整數陣列 nums ,

這個陣列只有一個元素只出現一次， 其他都成對出現

要求寫一個演算法來找出唯一出現的值