# Single Number Leetcode Solution

In this post, we are going to solve the Single Number Leetcode SolutionÂ problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.

## Problem

Given aÂ non-emptyÂ array of integersÂ `nums`, every element appearsÂ twiceÂ except for one. Find that single one.

You mustÂ implement a solution with a linear runtime complexity and useÂ only constantÂ 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 * 104Â <= nums[i] <= 3 * 104`
• Each element in the array appears twice except for one element which appears only once.

Now, letâ€™s see the leetcode solution ofÂ Single Number Leetcode Solution.

### Single Number Leetcode Solution in Python

```class Solution:
def singleNumber(self, nums: List[int]) -> int:
return functools.reduce(lambda x, y: x ^ y, nums, 0)```

### Single Number Leetcode Solutionin CPP

```class Solution {
public:
int singleNumber(vector<int>& nums) {
int ans = 0;

for (const int num : nums)
ans ^= num;

return ans;
}
};```

### Single Number Leetcode Solution in Java

```class Solution {
public int singleNumber(int[] nums) {
int ans = 0;

for (final int num : nums)
ans ^= num;

return ans;
}
}```

Note:Â This problem Single Number is generated byÂ LeetcodeÂ but the solution is provided byÂ Chase2learn This tutorial is only forÂ EducationalÂ andÂ LearningÂ purpose.

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