题解 | #牛牛的Hermite多项式#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static int result(int n, int x) {
	  //在函数中将题目的要求写出来即可
        if (n == 0) {
            return 1;
        } else if (n == 1) {
            return 2 * n;
        } else {
            return 2 * x * result((n - 1), x) - 2 * (n - 1) * result(n - 2, x);
        }
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int x = sc.nextInt();
        System.out.println(result(n, x));
    }
}