Subsets II（C++实现）

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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.

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

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

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  class Solution {public:    vector<vector<int> > subsetsWithDup(vector<int> &S) {        vector<vector<int> > ret;        if(S.size() == 0) return ret;        sort(S.begin(), S.end());        vector<int> tmp;        dfs(S, 0, tmp, ret);        return ret;    }        void dfs(vector<int> &S, int beg, vector<int> tmp, vector<vector<int> > &ret) {        ret.push_back(tmp);        if(beg >= S.size()) return;        for(int i = beg; i < S.size(); ++i) {            if(i == beg || S[i] != S[i-1]) {                tmp.push_back(S[i]);                dfs(S, i+1, tmp, ret);                tmp.pop_back();            }        }    }};

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