LeetCode: Subsets II

思路：先对原数组排个序，然后递归求解，注意重复元素的问题。

code:

class Solution {
public:
    vector<vector<int> > solve(vector<int> &S){
        vector<int> curRet;
        vector<vector<int> > ret;
        ret.push_back(curRet);
        if(S.size() == 0)
            return ret;
        vector<int> leftS(S.begin()+1,S.end());
        vector<vector<int> > leftRet = solve(leftS);
        for(int i = 0;i < leftRet.size();i++)
            if(leftRet[i].size() > 0) ret.push_back(leftRet[i]);
            
        for(int i = 0;i < leftRet.size();i++){
            leftRet[i].insert(leftRet[i].begin(),S[0]); 
            if(find(ret.begin(),ret.end(),leftRet[i]) == ret.end())
                ret.push_back(leftRet[i]);
        }
        return ret;
    }
    vector<vector<int> > subsetsWithDup(vector<int> &S) {
        vector<vector<int> > ret;
        sort(S.begin(),S.end());
        ret = solve(S);
        return ret;
    }
};