Subsets II 全排列包含重复的

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], [] ]

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