package algorithm.leetcode;

/**
 * @author: mayuan
 * @desc: 不同的二叉搜索树
 * https://leetcode.com/problems/unique-binary-search-trees/discuss/31666/DP-Solution-in-6-lines-with-explanation.-F(i-n)-G(i-1)-*-G(n-i)
 * @date: 2019/02/18
 */
public class Solution096 {
    public int numTrees(int n) {
        int[] dp = new int[n + 1];
        dp[0] = 1;
        dp[1] = 1;

        for (int i = 2; i <= n; ++i) {
            for (int j = 1; j <= i; ++j) {
                dp[i] += dp[j - 1] * dp[i - j];
            }
        }

        return dp[n];
    }
}