LeetCode Solution - Problem 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 * 104
• -3 * 104 <= nums[i] <= 3 * 104
• Each element in the array appears twice except for one element which appears only once.

Solution:

Java:

class Solution {
    public int singleNumber(int[] nums) {
        int ans = nums[0];
        for (int i=1; i < nums.length; i++) {
            ans = ans ^ nums[i];
        }
        return ans;
    }
}

Python3:

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        ans = nums[0]
        for i in range(1, len(nums)):
            ans = ans ^ nums[i]
        return ans