LeetCode OJ--Subsets II

https://oj.leetcode.com/problems/subsets-ii/

求一个集合的子集，但集合中有重复元素。

求子集的问题，对应着数的二进制，相当于对二进制的一个遍历。

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

class Solution {
public:
    vector<vector<int> > subsetsWithDup(vector<int> &S) {
        vector<vector<int> > ans;
        if(S.size()==0)
            return ans;
        int num = pow(2,S.size());
        sort(S.begin(),S.end());
        for(int i = 0; i<num; i++)
        {
            vector<int> ansPiece;
            ansPiece = oneSubsetPiece(i,S);
            bool flag = 1;
            for(int j = 1; j<ans.size(); j++)
            {
                if(ansPiece == ans[j]) flag = 0;
            }
            if(flag == 1)
                ans.push_back(ansPiece);
        }
        return ans;
    }
    //find the num's binary
    vector<int> oneSubsetPiece(int num,vector<int> &S)
    {
        vector<int> ansPiece;
        int YuShu;
        int ChuShu;
        int index = 0;
        while(num)
        {
            YuShu = num %2;
            num = num/2;
            if(YuShu)
                ansPiece.push_back(S[index]);
            index++;
        }
        return ansPiece;
    }
};

int main()
{
    class Solution sol;
    vector<int> num;
    num.push_back(1);
    num.push_back(2);
    num.push_back(2);
    sol.subsetsWithDup(num);
}