Single Number

Core

10000ms500MB

You are given a non-empty integer array nums in which every value appears exactly twice, except for one value that appears exactly once.

Return the value that appears once.

You must write an algorithm that runs in $O(n)$ time and uses only $O(1)$ extra space.

Examples

Example 1

Input: nums = [2, 2, 1]
Output: 1
Explanation: The value 2 appears twice; 1 is the value that appears once.

Example 2

Input: nums = [4, 1, 2, 1, 2]
Output: 4

Example 3

Input: nums = [1]
Output: 1

Constraints

$1 \leq$ nums.length $\leq 3 \cdot 10^4$
$-3 \cdot 10^4 \leq$ nums[i] $\leq 3 \cdot 10^4$
every value in nums appears exactly twice, except one value that appears exactly once

Examples

Example 1

Input

nums = [2, 2, 1]

Output

Example 2

Input

nums = [4, 1, 2, 1, 2]

Output

Example 3

Input

nums = [1]

Output

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Click "Run" to test with sample cases or "Submit" to run all tests.

Single Number

Core

10000ms500MB

You are given a non-empty integer array nums in which every value appears exactly twice, except for one value that appears exactly once.

Return the value that appears once.

You must write an algorithm that runs in $O(n)$ time and uses only $O(1)$ extra space.

Examples

Example 1

Input: nums = [2, 2, 1]
Output: 1
Explanation: The value 2 appears twice; 1 is the value that appears once.

Example 2

Input: nums = [4, 1, 2, 1, 2]
Output: 4

Example 3

Input: nums = [1]
Output: 1

Constraints

$1 \leq$ nums.length $\leq 3 \cdot 10^4$
$-3 \cdot 10^4 \leq$ nums[i] $\leq 3 \cdot 10^4$
every value in nums appears exactly twice, except one value that appears exactly once

Examples

Example 1

Input

nums = [2, 2, 1]

Output

Example 2

Input

nums = [4, 1, 2, 1, 2]

Output

Example 3

Input

nums = [1]

Output

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Click "Run" to test with sample cases or "Submit" to run all tests.