# [LeetCode]96.Unique Binary Search Trees

2014-12-27

【题目】 Given n, how many structurally unique BST & 039;s (binary search trees) that store values 1 n? For example, Given n = 3, there are a total of 5 unique BST & 039;s

#### 【题目】

Given n, how many structurally unique BST's (binary search trees) that store values 1...n?

For example,
Given n = 3, there are a total of 5 unique BST's.

```   1         3     3      2      1
\       /     /      / \      \
3     2     1      1   3      2
/     /       \                 \
2     1         2                 3```

#### 【代码】

```/*********************************
*   日期：2014-12-26
*   作者：SJF0115
*   题目: 96.Unique Binary Search Trees
*   来源：https://oj.leetcode.com/problems/unique-binary-search-trees/
*   结果：AC
*   来源：LeetCode
*   总结：
**********************************/
#include
#include
using namespace std;

class Solution {
public:
int numTrees(int n) {
vector f(n+1,0);
f[0] = 1;
f[1] = 1;
for(int i = 2;i <= n;i++){
for(int j = 1;j <= i;j++){
f[i] += f[j-1] * f[i-j];
}//for
}//for
return f[n];
}
};

int main() {
Solution solution;
cout<

```