using prev

class Solution {
    List<List<Integer>> res = new ArrayList<List<Integer>>();
    public List<List<Integer>> subsets(int[] nums) {
        List<Integer> temp = new ArrayList<>();
        back(temp,nums, 0);
        return res;
    }
    void
 
 back(List<Integer> temp,int[] nums, int prev){
        List<Integer> list = new ArrayList<>(temp);
        //if(!res.contains(list))
        res.add(list);
        
        for(int i = prev; i<nums.length; i++){
            temp.add(nums[i]);
            back(temp, nums, i+1);
            temp.remove(temp.size()
 
-1);
        }
    }
}

// 90 subset2

sorting the array first and check the contains

class Solution {
    List<List<Integer>> res = new ArrayList<List<Integer>>();
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<Integer> temp = new ArrayList<>();
        Arrays.sort(nums);
        back(temp,nums, 
 
0);
        return res;
    }
    void back(List<Integer> temp,int[] nums, int prev){
        List<Integer> list = new ArrayList<>(temp);
        if(!res.contains(list))
        res.add(list);
        
        for(int i = prev; i<nums.length; i++){
            temp.add(nums[i]);
            back(temp, nums, i+1);
            temp.remove(temp.size()-1);
        }
    }

}

Leetcode 78. Subsets (backtracking) 90 subset