Subsets II

Given a collection of integers that might contain duplicates, 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 = [1,2,2], a solution is:

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

 

Code:

?

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