动态规划系列一＞卡特兰数-不同的二叉搜索树

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

        return dp[n];        
    }
}