class Solution {
public:
    void int_to_bool(int n,vector<int>&index)
    {
        int len=index.size();
        index.clear();
        index.resize(len);
        int i=0;
        while(n)
        {
            int temp=n%2;
            index[i]=temp;
            i++;
            n/=2;
        }
    }
    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>> res;
        if(nums.size()==0) return res;
        sort(nums.begin(),nums.end());
        int len=nums.size();
        int max=(1<<nums.size());
        vector<int> index(len,0);
        for(int i=0;i<max;i++)
        {
            int_to_bool(i,index);
            vector<int> temp;
            for(int j=0;j<len;j++)
            {
                if(index[j]==1)
                temp.push_back(nums[j]);
            }
            res.push_back(temp);
        }
        return res;
    }
};