LeetCode 78. Subsets

78. Subsets

Problem

Given an integer array nums of unique elements, return all possible subsets (the power set).

The solution set must not contain duplicate subsets. Return the solution in any order.

Questions before reading example

• nums empty?
• min/max length? unique?
• empty subset?

Example

Input: nums = [1,2,3]
Output: [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]

Input: nums = [0]
Output: [[],[0]]

Solution

• 나의 풀이

  class Solution {
  
  public List<List<Integer>> subsets(int[] nums) {
  
    List<List<Integer>> results = new ArrayList<>();
    backtracking(nums, new ArrayList<>(), results, 0);
    return results;
  }
  
  private void backtracking(int[] nums, List<Integer> candidates, List<List<Integer>> results, int start) {
    results.add(new ArrayList<>(candidates));
    for (int i = start; i < nums.length; i++) {
      candidates.add(nums[i]);
      backtracking(nums, candidates, results, i + 1);
      candidates.remove(candidates.size() - 1);
    }
  
  
  }
  }
  

Spent time

Review

• 46 Permutations 에 이어 연속적으로 풀어본 백트래킹 문제
• 풀이법이 거의 비슷하다
• 주요 포인트는 results.add(new ArrayList<>(candidates));