# Участник:Никита Плетнев/unique binary search trees ii

Перейти к: навигация, поиск
```/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode() : val(0), left(nullptr), right(nullptr) {}
*     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
*     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
vector<TreeNode*> allTreesFromRange(int begin_, int end_) {
vector<TreeNode*> result;
if (begin_ >= end_) {
result.push_back(NULL);
return result;
}
for (int m = begin_; m < end_; ++m) {
vector<TreeNode*> left_subtrees = allTreesFromRange(begin_, m);
vector<TreeNode*> right_subtrees = allTreesFromRange(m + 1, end_);
for (auto it = left_subtrees.begin(); it < left_subtrees.end(); ++it) {
for (auto jt = right_subtrees.begin(); jt < right_subtrees.end(); ++jt) {
TreeNode* root = new TreeNode(m, *it, *jt);
result.push_back(root);
}
}
}
return result;
}

vector<TreeNode*> generateTrees(int n) {
if (n == 0)
return {};
return allTreesFromRange(1, n + 1);
}
};```