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 int count=0;
    public static int[] dx={0,1};
    public static int[] dy={1,0};
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt()+1;
        int m=sc.nextInt()+1;
        int[][] arr=new int[n][m];
        arr[0][0]=1;
        dfs(arr,0,0);
        System.out.println(count);
    }
    public static void dfs(int[][] arr,int i,int j){
        if(i==arr.length-1&&j==arr[i].length-1){
            count++;
            return;
        }
        for (int k = 0; k < 2; k++) {
            int i1=i+dx[k];
            int j1=j+dy[k];
            if (i1>=0&&i1<arr.length&&j1>=0&&j1<arr[i].length&&arr[i1][j1]==0){
                arr[i1][j1]=1;
                dfs(arr,i1,j1);
                arr[i1][j1]=0;
            }
        }
    }
}