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],
  []
]
思路：这道题在Subsets基础上，添加了重复元素，然而在最后的结果当中不能有重复的vector出现，也就是在组合这些整数的时候要加一些限制条件。

class Solution {
public:
    void find(vector<vector<int> > &result,vector<int> &S,vector<int> data,int index)
    {
        result.push_back(data);
        for(int i=index;i<S.size();i++)
        {
            if(i!=index&&S[i]==S[i-1])
                continue;
            data.push_back(S[i]);
            find(result,S,data,i+1);
            data.pop_back();
        }
    }
    vector<vector<int> > subsetsWithDup(vector<int> &S) {
        vector<vector<int> > result;
        vector<int> data;
        result.clear();
        if(S.empty())
            return result;
        sort(S.begin(),S.end());
        find(result,S,data,0);
        return result;
    }
};