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[] G = new int[n+1];
        G[0] = G[1] = 1;
        for(int i = 2; i <= n; i++){
            for( int j = 1; j <= i; j++){
                G[i] += G[j-1]*G[i-j];
            }
        }
        return G
;
    }
}

https://leetcode.com/discuss/24282/dp-solution-in-6-lines-with-explanation-f-i-n-g-i-1-g-n-i https://github.com/zxysnow/leetcode/commit/7cf306e7b9eb8841371f926a5ac51b524c96138a