[LeetCode] #90 Subset II

public class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        if (nums == null ||nums.length == 0) {
            return result;
        }
        Arrays.sort(nums);
        helper(result, new ArrayList<Integer>(), nums, 0);
        return result;
    }
    
    private void helper(List<List<Integer>> result, List<Integer> path, int[] nums, int start) {
        result.add(new ArrayList<Integer>(path));
        
        for (int i = start; i < nums.length; i++) {
            if (i > 0 && i != start && nums[i] == nums[i - 1]) {
                continue;
            }
            path.add(nums[i]);
            helper(result, path, nums, i + 1);
            path.remove(path.size() - 1);
        }
    }
}