0137. Single Number II

https://leetcode.com/problems/single-number-ii

Description

Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.

You must implement a solution with a linear runtime complexity and use only constant extra space.

Example 1:

**Input:** nums = [2,2,3,2]
**Output:** 3

Example 2:

**Input:** nums = [0,1,0,1,0,1,99]
**Output:** 99

Constraints:

• 1 <= nums.length <= 3 * 104

• -231 <= nums[i] <= 231 - 1

• Each element in nums appears exactly three times except for one element which appears once.

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