Unique Binary Search Trees

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

int numTrees(int n) {

	vector<int> SumNumtrees(n + 1, 1);
	for (int i = 2; i <= n; ++i){
		SumNumtrees[i] = 0;
		for (int k = 0; k < i; ++k)
		{
			SumNumtrees[i] += SumNumtrees[k] * SumNumtrees[i - k - 1];
		}
	}
	return SumNumtrees[n];
}

Unique Binary Search Trees

原文：http://blog.csdn.net/li_chihang/article/details/44649129