题解 | #走方格的方案数#先想出递归方案再动规

import java.util.*;
import java.util.stream.*;
import java.util.regex.*;
import java.util.function.*;

// 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);
        // 注意 hasNext 和 hasNextLine 的区别

        // System.out.println(move(in.nextInt(), in.nextInt()));
        int n = in.nextInt();
        int m = in.nextInt();

        int[][] d = new int[n+1][m+1];
        for (int i = 0; i < n+1; i++) {
            d[i][1] = i+1;
        }
        for (int i = 0; i < m+1; i++) {
            d[1][i] = i+1;
        }

        for (int i = 2 ; i < n +1; i++) {
            for(int j = 2; j < m+1 ;j++) {
                d[i][j] = d[i-1][j] + d[i][j-1];
            }
        }
        System.out.println(d[n][m]);
    }

    static int move(int n, int m) {
        if ( m == 1 ) {
            return n + 1;
        }
        if  (n == 1) {
            return m + 1;
        }

        return move(n-1, m) + move(n, m-1);
    }
}