[LeetCode] Unique Binary Search Trees

Thought:
Recursion. We could also use DP to do faster.

Code:
public class Solution {
    public int numTrees(int n) {
        if (n < 2) return 1;
        if (n == 2) return 2;
        int result = 0;
        for (int i = 0; i < n; i++) {
            result = result + numTrees(i) * numTrees(n - i - 1);
        }
        return result;      
    }
}