Java 代码

import java.util.Scanner;

public class Main
{
    public static void main(String[] args)
    {
        Scanner cin = new Scanner(System.in);

        int n = cin.nextInt();

        int center = n / 2;

        for (int i = 0; i < n; i ++)
        {
            for (int j = 0; j < n; j ++)
            {
                if ((Math.abs(i - center) + Math.abs(j - center)) <= n/2)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            System.out.print("\n");
        }
    }

}