[LeetCode105]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],
  []
]

Analysis:

DFS. Similar with Subsets, difference here is to remove duplicate numbers.

Java

public class Solution {
    List<List<Integer>> result;
	List<Integer> solu;
	public List<List<Integer>> subsetsWithDup(int[] num) {
        result = new ArrayList<>();
        solu = new ArrayList<>();
        Arrays.sort(num);
        getSubset(num, 0);
        return result;
    }
	public void getSubset(int[] num, int st){
		if(solu.size()<=num.length){
			result.add(new ArrayList<>(solu));
		}
		for(int i=st;i<num.length;i++){
			solu.add(num[i]);
			getSubset(num, i+1);
			solu.remove(solu.size()-1);
			while(i<num.length-1 && num[i]==num[i+1]) i++;
		}
	}
}

c++

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