[LeetCode] Subsets

Subsets

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

Note:

• Elements in a subset must be 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],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

Solution: The beauty of recursion!

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public class Solution { public List<List<Integer>> subsets(int[] nums) { ArrayList<List<Integer>> list = new ArrayList<List<Integer>>(); if (nums.length == 0) { ArrayList<Integer> l = new ArrayList<Integer>(); list.add(l); return list; } Arrays.sort(nums); List<List<Integer>> li = subsets( Arrays.copyOfRange(nums, 0, nums.length - 1) ); list.addAll(li); for (List<Integer> ll : li) { ArrayList<Integer> l = new ArrayList<Integer>(ll); l.add(nums[nums.length - 1]); list.add(l); } return list; } }