题解 | 二维斐波那契数列

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 scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        scanner.close();

        final int MOD = 1000000007;
        long[][] dp = new long[n + 1][m + 1];

        // 初始化第一行和第一列
        for (int i = 1; i <= n; i++) {
            dp[i][1] = 1;
        }
        for (int j = 1; j <= m; j++) {
            dp[1][j] = 1;
        }

        // 递推计算其他位置的值
        for (int i = 2; i <= n; i++) {
            for (int j = 2; j <= m; j++) {
                dp[i][j] = (dp[i - 1][j] + dp[i][j - 1]) % MOD;
            }
        }

        System.out.println(dp[n][m]);
    }
}