题解 | 走方格的方案数

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 void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int m = in.nextInt(); // 行数
        int n = in.nextInt(); // 列数
        System.out.println(countPaths(m, n));
    }

    public static int countPaths(int m, int n) {
        int totalSteps = m + n;//总行数
        int stotalSteps=1,sm =1,sn=1;
        for (int i = 1; i <= totalSteps; i++) {
            stotalSteps *= i;
        }
        for (int i = 1; i <= m; i++) {
            sm *= i;
        }
        for (int i = 1; i <= n; i++) {
            sm *= i;
        }
        return stotalSteps / (sm * sn);
    }
}