Java 代码

import java.util.Scanner;

public class Main
{
    public static int row = 0;
    public static int col = 0;

    public static int ans = 0;

    public static void dfs (int x, int y)
    {
        if (x == row && y == col)
            ans += 1;
        else
        {
            if (x < row)
                dfs (x + 1, y);

            if (y < col)
                dfs (x, y + 1);
        }
    }

    public static void main (String[] args)
    {
        Scanner cin = new Scanner(System.in);

        row = cin.nextInt();
        col = cin.nextInt();

        dfs (0, 0);
        System.out.println (ans);
    }
}