Subsets

Given a set of distinct integers, S, return all possible subsets.

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

 

For example,
If S = [1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

 

 Code:

?

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class Solution { public:     void findSub(vector<int> &S, int &n, int level, vector<int> &buf, vector<vector<int>> &res){         if(buf.size()==n){             res.push_back(buf);             return;         }         for(int i=level;i<S.size();i++){             buf.push_back(S[i]);             findSub(S,n,i+1,buf,res);             buf.pop_back();         }     }     vector<vector<int> > subsets(vector<int> &S) {         vector<vector<int>> res;         vector<int> buf;         sort(S.begin(),S.end());         for(int i=0;i<=S.size();i++)             findSub(S,i,0,buf,res);         return res;     } };