subsets

class Solution {
public:
    vector<vector<int>>ans;
    vector<int>path;
    vector<vector<int> > subsets(vector<int> &S) {
        sort(S.begin(),S.end());
        if(S.size()==0)return ans;
        dfs(S,0);
        sort(ans.begin(),ans.end(),comp);
        return ans;
    }
    void dfs(vector<int>S,int index)
    {
        if(index==S.size())
        {
            ans.push_back(path);
            return;
        }
        path.push_back(S[index]);
        dfs(S,index+1);
        path.pop_back();
        dfs(S,index+1);
    }
    static bool comp(vector<int>a,vector<int>b){
        if(a.size()<b.size())return true;
        else if(a.size()==b.size())return a<b;
        else return false;
    }
};