https://leetcode-cn.com/problems/single-number/
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 * 10^4
-3 * 10^4 <= nums[i] <= 3 * 10^4
Each element in the array appears twice except for one element which appears only once.
class Solution:
def singleNumber(self, nums: List[int]) -> int:
ans=0
for num in nums:
ans=ans^num
return ans