import java.util.ArrayDeque;

import java.util.ArrayList;

import java.util.Deque;

import java.util.List;

/**

* Description: 子集

* Date: 2020-11-17

* Time: 10:48 PM

*/

public class Subsets2 {

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

int len = nums.length;

List<List<Integer>> res = new ArrayList<>();

if (len == 0) {

return res;

}

Deque<Integer> path = new ArrayDeque<>();

dfs(nums,len,0,path, res);

return res;

}

private void dfs(int[] nums, int len,int begin,Deque<Integer> path,List<List<Integer>> res) {

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

for (int i = begin; i < len; i++) {

path.addLast(nums[i]);

dfs(nums, len, i + 1, path, res);

path.removeLast();

}

}

public static void main(String[] args) {

System.out.println(new Subsets2().subsets(new int[]{1,2,3}));

}

}