package com.github.lifelab.leetcode.problemset;

import java.util.LinkedList;

import java.util.List;

/**

* 子集 @see https://leetcode-cn.com/problems/subsets/

*

* @author Weichao Li (liweichao0102@gmail.com)

* @since 2019-06-30

*/

public class Solution78 {

public List<List<Integer>> subsets(int[] nums) {

List<List<Integer>> list = new LinkedList<>();

traverse(nums, 0, list, new LinkedList<>());

return list;

}

private void traverse(int[] nums, int index, List<List<Integer>> list, List<Integer> currentList) {

// terminator

if (nums.length == index) {

list.add(currentList);

return;

}

// process & drill down

List<Integer> target = new LinkedList<>(currentList);

target.add(nums[index]);

traverse(nums, index + 1, list, currentList);

traverse(nums, index + 1, list, target);

}

}