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

public class Solution {
    public int numTrees(int n) {
        int[] C = new int[n+1];
        C[0] = 1;
        for (int i = 1; i <= n; i++) {
        	for (int j = 0; j <= i-1; j++) {
        		C[i] += C[j]*C[i-1-j];
        	}
        }
        return C[n];
    }
}