子集2 含有重复元素

public static Listtask1(int[] nums){

back(nums,0,new ArrayList());

    return result;

}

public static void back(int[] nums, int start, ArrayList path){

result.add(new ArrayList<>(path));

    for(int i = start;i

if (i>start && nums[i]== nums[i-1] ){

continue;

        }

path.add(nums[i]);

        back(nums,i+1,path);

        path.remove(path.size()-1);

    }

}