0078. Subsets

class Solution {
    /* global valiable and local have same time complexity*/
    //static HashSet<List<Integer>> hs = new HashSet<>();
    //static List<List<Integer>> res = new LinkedList<List<Integer>>();
    
    public static void tempo(int nums[],int c,List<Integer> lix,List<List<Integer>> res){
        //no duplicates so no need to check for redundant
        //hs.add(new ArrayList(lix));
        res.add(new ArrayList(lix));
        for(;c<nums.length;c++){
            lix.add(nums[c]);
            tempo(nums,c+1,lix,res);
            lix.remove(lix.size()-1);
        }
        return;
    }
    
    public List<List<Integer>> subsets(int[] nums) {
        //Arrays.sort(nums);
        //hs.clear();
        //res.clear();
        List<List<Integer>> res = new LinkedList<List<Integer>>();
        tempo(nums,0,new LinkedList<Integer>(),res);
        
        return res;
    }
}