题解 | #空心正方形图案#

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        while (scan.hasNext()) {
            int n = scan.nextInt();
            for (int i = 1; i <= n; i++) {
                if (i != 1 && i != n) {
                    System.out.print("* ");
                    for (int j = 1; j <= n - 2; j++) System.out.print("  ");
                    System.out.print("* ");
                } else
                    for (int j = 1; j <= n; j++) {
                        System.out.print("* ");
                    }
                System.out.println();
            }
        }
    }
}