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],
  []
]

class Solution {
    
    List<List<Integer>> res = new ArrayList<>();
    
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        Arrays.sort(nums);
        help(new ArrayList<>(), nums, 0);
        return res;
    }
    private void help(List<Integer> temp,int[] nums,int index){
        temp = new ArrayList<>(temp);
        res.add(temp);
        for(int  i= index;i<nums.length;i++){
            if(i>index&&nums[i]==nums[i-1])
                continue;
            temp.add(nums[i]);
            help(temp,nums,i+1);
            temp.remove(temp.size()-1);
        }
    }
}