90. Subsets II

Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set).

Note: The solution set must not contain duplicate subsets.

Example:

Input: [1,2,2]
Output:
[
  [2],
  [1],
  [1,2,2],
  [2,2],
  [1,2],
  []
]

 1 class Solution {
 2     
 3     List<List<Integer>> res = new ArrayList<>();
 4     
 5     public List<List<Integer>> subsetsWithDup(int[] nums) {
 6         Arrays.sort(nums);
 7         help(new ArrayList<>(), nums, 0);
 8         return res;
 9     }
10     private void help(List<Integer> temp,int[] nums,int index){
11         temp = new ArrayList<>(temp);
12         res.add(temp);
13         for(int  i= index;i<nums.length;i++){
14             if(i>index&&nums[i]==nums[i-1])
15                 continue;
16             temp.add(nums[i]);
17             help(temp,nums,i+1);
18             temp.remove(temp.size()-1);
19         }
20     }
21 }