Increasing Subsequences LeetCode solution in Java

1
class Solution {
2
  HashSet<List<Integer>> set;
3

4
  public List<List<Integer>> findSubsequences(int[] nums) {
5
    set = new HashSet<>();
6

7
    dfs(nums, 0, new ArrayList<>());
8

9
    List<List<Integer>> ans = new ArrayList<>();
10
    if (set.size() > 0) {
11
      ans.addAll(set);
12
    }
13
    return ans;
14
  }
15

16
  private void dfs(int nums[], int start, List<Integer> temp) {
17
    if (start == nums.length) return;
18

19
    for (int i = start; i < nums.length; i++) {
20
      if (temp.size() == 0 || temp.get(temp.size() - 1) <= nums[i]) {
21
        temp.add(nums[i]);
22

23
        if (temp.size() >= 2) set.add(new ArrayList<>(temp));
24

25
        dfs(nums, i + 1, temp);
26
        temp.remove(temp.size() - 1);
27
      }
28
    }
29
  }
30
}