标题：
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
     
      
       > subsetsWithDup(int[] num) { 3         ArrayList
       
        
         > res=new ArrayList
         
          
           >(); 4 ArrayList
           
             tmp=new ArrayList
            
             (); 5 Arrays.sort(num); 6 dfs(res,tmp,0,num); 7 return res; 8 } 9 public void dfs(ArrayList
             
              
               > res,ArrayList
               
                 tmp,int start,int[] num){10 if(!res.contains(tmp))11 res.add(new ArrayList
                
                 (tmp));12 for(int i=start;i