题解 | #空心正方形图案#

import java.util.Scanner;
public class Main {
    
    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextInt()) {
            int n = sc.nextInt();
            for(int i = 1 ; i <= n ; i++) {
                if(i == 1 || i == n) {
                    for(int j = 1 ; j <= n ; j ++) {
                        System.out.print("* ");
                    }
                    System.out.println();
                } else {
                    for(int j = 1 ; j <= n ; j ++) {
                        if(j == 1 || j == n) {
                            System.out.print("* ");
                        } else {
                            System.out.print("  ");
                        }
                    }
                    System.out.println();
                }
            }
        }
    }
}