【算法】位运算算法——只出现一次的数字Ⅱ

class Solution {
public:
    int singleNumber(vector<int>& nums) 
    {
        int ret = 0;
        for(int i = 0; i < 32; i++)
        {   
            int sum = 0;
            for(auto& num : nums)
            {
                if(((num>>i) & 1) == 1)
                sum++;
            }
            sum = sum % 3;
            //如果sum = 1，说明ret那个对应比特位修改为1
            if(sum == 1) ret = (ret | (1 << i)); 
        }
        return ret;
    }
};