LeetCode 96. Unique Binary Search Trees

public class Solution {    public int numTrees(int n) {        int nums[] = new int[n + 1];        nums[0] = nums[1] = 1;        for (int i = 2; i <= n; i++) {        for (int j = 1; j <= i; j++) {        nums[i] += nums[j - 1] * nums[i - j];        }        }        return nums[n];    }}