LeetCode:Subsets

Subsets

Given a set of distinct integers, 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 = [1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

public class Solution {
    public ArrayList<ArrayList<Integer>> subsets(int[] S) {
        
        if(S==null) return null;
        Arrays.sort(S);
        ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
                                     
        for(int i=0;i<S.length;i++){
            ArrayList<ArrayList<Integer>> cur = new ArrayList<ArrayList<Integer>>();
            for(ArrayList<Integer> temp:res){
                cur.add(new ArrayList<Integer>(temp));
            }
            
            for(ArrayList<Integer> temp:cur){
                temp.add(S[i]);
            }
            
            ArrayList<Integer> temp1 = new ArrayList<Integer>();
            temp1.add(S[i]);
            cur.add(temp1);
            
            res.addAll(cur);
        }
        res.add(new ArrayList<Integer>());
        return res;
    }
}