leetcode------Subsets II

标题：	Subsets II
通过率：	27.5
难度：	中等

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],
  []
]

从第一个版本中可以看出来，这里需要增加相同判断。具体看代码

 1 public class Solution {
 2     public ArrayList<ArrayList<Integer>> subsetsWithDup(int[] num) {
 3         ArrayList<ArrayList<Integer>> res=new ArrayList<ArrayList<Integer>>();
 4         ArrayList<Integer> tmp=new ArrayList<Integer>();
 5         Arrays.sort(num);
 6         dfs(res,tmp,0,num);
 7         return res;
 8     }
 9     public void dfs(ArrayList<ArrayList<Integer>> res,ArrayList<Integer> tmp,int start,int[] num){
10         if(!res.contains(tmp))
11             res.add(new ArrayList<Integer>(tmp));
12         for(int i=start;i<num.length;i++){
13             tmp.add(num[i]);
14             dfs(res,tmp,i+1,num);
15             tmp.remove(tmp.size()-1);
16         }
17     }
18 }