Given a set of distinct integers, nums, return all possible subsets (the power set).
Note: The solution set must not contain duplicate subsets.
Example:
Input: nums = [1,2,3] Output: [ [3], [1], [2], [1,2,3], [1,3], [2,3], [1,2], [] ]
难度:medium
题目:给定一不含重复元素的集合,求其所有子集。
注意:答案不能包含重复的子集。
思路:递归
Runtime: 1 ms, faster than 100.00% of Java online submissions for Subsets.
Memory Usage: 37.2 MB, less than 0.96% of Java online submissions for Subsets.
class Solution { public List<List<Integer>> subsets(int[] nums) { List<List<Integer>> result = new ArrayList<>(); for (int i = 0; i < nums.length; i++) { subsets(nums, 0, i + 1, new Stack<>(), result); } result.add(new ArrayList<>()); return result; } private void subsets(int[] nums, int idx, int k, Stack<Integer> stack, List<List<Integer>> result) { if (k <= 0) { result.add(new ArrayList<>(stack)); return; } for (int i = idx; i < nums.length - k + 1; i++) { stack.push(nums[i]); subsets(nums, i + 1, k - 1, stack, result); stack.pop(); } } }