Single Number II

main.cpp

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        auto it = nums.begin(),end = nums.end();
        int o = 0,t = 0;
        while(it != end){
            int oo = o;
            o = (o^(*it))&(~(t&*it));
            t = (~(t&(*it))) & (oo & (*it) | t);
            ++it;
        }
        return o;
    }
};