powerset.java

import java.util.List;
import java.util.ArrayList;

public class powerset {
    public static List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>> list = new ArrayList<>();
        findSubsets(nums,list,new ArrayList<>(),0);
        return list;
    }
    
    public static void findSubsets(int[] nums,List<List<Integer>> list,ArrayList<Integer> temp,int i){
        if(i>=nums.length){
            list.add(new ArrayList<>(temp));
            return;
        }
        
        findSubsets(nums,list,temp,i+1);
        temp.add(nums[i]);
        findSubsets(nums,list,temp,i+1);
        temp.remove(temp.size()-1);
    }
    public static void main(String[] args) {
      int nums[]= {3,1,2};
      System.out.println(subsets(nums));
    }
}