java输入一个整数打印，假如输入4打印如下： 1 2 3 4 8 7 6 5 9 10 11 12 16 15 14 13

以下是 Java 代码实现：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        System.out.print("请输入一个整数: ");
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int[][] matrix = new int[n][n];

        int num = 1;
        for (int i = 0; i < n; i++) {
            if (i % 2 == 0) {
                for (int j = 0; j < n; j++) {
                    matrix[i][j] = num++;
                }
            } else {
                for (int j = n - 1; j >= 0; j--) {
                    matrix[i][j] = num++;
                }
            }
        }

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}

如果输入4，则输出如下：

1 2 3 4 
8 7 6 5 
9 10 11 12 
16 15 14 13