leetcode subsets c++

dfs needs more practice.

class Solution {public:    vector<vector<int> > subsets(vector<int> &S) {  vector<vector<int> > answer;  vector<int> cur;  answer.push_back(cur);  if(S.empty())  return answer;  sort(S.begin(),S.end());  for(int i = 1;i<=S.size();i++)  {  dfs(S,0,i,cur,answer);  }   return answer;    }    void dfs(vector<int> &S,int start,int num,vector<int> &cur, vector<vector<int>> &answer)  {  if(num == cur.size())  {  answer.push_back(cur); return;   }  for(int i = start ;i<S.size();i++)  {  cur.push_back(S[i]);  dfs(S,i+1,num,cur,answer);  cur.pop_back();  }  }};