leetcode

0 class Solution {

1 vector<TreeNode *> dp[10][10];

2

3 vector<TreeNode *> rec(int n, int left, int right) {

4 vector<TreeNode *> &res = dp[left][right];

5 if (!res.empty()) return res;

6

7 for (int i = left; i <= right; i++) {

8 for (const auto &l : rec(n, left, i - 1)) {

9 for (const auto &r : rec(n, i + 1, right)) {

10 res.push_back(new TreeNode(i, l, r));

11 }

12 }

13 }

14 if (res.empty()) return {nullptr};

15 return res;

16 }

17

18 public:

19 vector<TreeNode *> generateTrees(int n) { return rec(n, 1, n); }

20 };