Top 150 Interview簡単

Single Number

Detailed guide and Python implementation for the 'Single Number' problem.

問題提起

簡単

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.

Write a function singleNumber(nums: List[int]) -> int.

制約
  • 1 <= len(nums) <= 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

Example 1
Input
nums = [2,2,1]
Output
1
Explanation

The element 1 appears once.

Example 2
Input
nums = [4,1,2,1,2]
Output
4
Explanation

The element 4 appears once.

Example 3
Input
nums = [1]
Output
1
Explanation

The element 1 appears once.

Need a Hint?
Consider using Bit Manipulation-specific data structures like sets or heaps.
Edge Cases to Watch
  • Empty input structures
  • Single element inputs
  • Large numerical bounds

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