notes/OJ notes/pages/Leetcode Single-Number.md

# Leetcode Single-Number

#### 2022-07-22 15:31

> ##### Algorithms:
> #algorithm #bit_manipulation 
> ##### Data structures:
> #DS #bitset
> ##### Difficulty:
> #coding_problem #difficulty-easy 
> ##### Additional tags:
> #leetcode 
> ##### Revisions:
> N/A

##### Related topics:
```expander
tag:#bit_manipulation
```
 
 

##### Links:
- [Link to problem](https://leetcode.com/problems/single-number/)
- [Learn about XOR]()
___
### Problem

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.

### Thoughts

> [!summary]
> This is a #bit_manipulation problem utilizing the XOR operator



### Solution