LeetCode | Single Number II

Given an array of integers, every element appears three times except for one. Find that single one.

Note:

Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

#include <iostream>
#include <vector>
using namespace std;

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

int main(int argc, char const *argv[])
{
	int a[] = {3,4,4,4};
	vector<int>nums(a,a+4);
	Solution S;
	cout<<S.singleNumber(nums)<<endl;
	return 0;
}