78. Subsets -Medium

Question

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

Note: The solution set must not contain duplicate subsets.

给出一个无重复整数的集合nums，返回所有可能的子集（子集不能重复）

Example

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

[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]

Solution

• 回溯解。遍历以当前元素为头的子集并保存结果即可

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