class Solution {
public:
int singleNumber(vector<int>& nums) {
int ans = 0;
for(int ii = 0; ii < 32; ii++) {
int bit = 1 << ii;
int cnt = 0;
for(auto num : nums) {
if(bit & num) cnt++;
}
if(cnt % 3) ans |= bit;
}
return ans;
}
};