137. Single Number II

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137. 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:

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

Example 2:

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

Constraints:

  • 1 <= nums.length <= 3 * 10^4
  • -2^31 <= nums[i] <= 2^31 - 1
  • Each element in nums appears exactly three times except for one element which appears once .

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int loner = 0, n = nums.size();
        for (int i = 0; i < 32; i++) {
            int sum = 0;
            for (int j = 0; j < n; j++) {
                if ((nums[j] >> i) & 1) {
                    sum++;
                }
            }
            loner |= (sum % 3) << i;
        }
        return loner;
    }
};