[Leetcode] [Java] Subsets

Title:

Given a set of distinct integers, nums, return all possible subsets.

Note:

• Elements in a subset must is in non-descending order.
• The solution set must not contain duplicate subsets.

For example,
If nums = [1,2,3] , a solution is:

[  3],  [1], [2], [1,3], [+]  ,  [2,3], [up  ],  []]

Test Instructions:

Given an array of different numbers, Nums returns all the subsets in this array.

Attention:
1. The elements in the sub-set must be in ascending order

2. The final result cannot contain a duplicate subset.

Algorithm Analysis:

Combined with the previous question "combinations" method, the previous question as a sub-function to use.

AC Code:

<span style= "Font-family:microsoft yahei;font-size:12px;" >public class Solution {public arraylist<arraylist<integer>> subsets (int[] nums) {ArrayList        <ArrayList<Integer>> fres = new arraylist<arraylist<integer>> ();        arraylist<integer> flist= new arraylist<integer> ();        Arrays.sort (Nums);        Fres.add (flist); for (int i=1;i<=nums.length;i++) {arraylist<arraylist<integer>> sres = new Arraylist<array        List<integer>> ();        Sres=combine (Nums, i);        Fres.addall (Sres);    } return fres; } public static arraylist<arraylist<integer>> combine (int nums[], int k) {Arraylist<arraylis        t<integer>> res = new arraylist<arraylist<integer>> ();         if (nums.length<=0 | | nums.length<k) return res;        Helper (Nums,k,0,new arraylist<integer> (), res);    return res; } private static void helper (int nums[], int k, int start, arraylist<integer> item, ARRAYLIST&LT;ARRAYLIST&LT;INTEGER&GT;&GT ;            RES) {if (Item.size () ==k) {Res.add (new arraylist<integer> (item));         Return } for (int i=start;i<nums.length;i++)//try per possibility number in current position {I             Tem.add (Nums[i]); Helper (nums,k,i+1,item,res); After selecting number for the current position, process next position item.remove (Item.size ()-1); Clear the current position to try next possible number}}}</span>

Copyright NOTICE: This article is the original article of Bo Master, reprint annotated source

[Leetcode] [Java] Subsets