题解 | #空心正方形图案#

#include <stdio.h>

int main() {
	int n = 0, i = 0, j = 0;

	while (scanf("%d", &n) != EOF) {
		int right = 2 * n - 1; /*每行元素个数*/
		for (i = 1; i <= n; i++) /*共n行*/ {
			if (i >= 2 && i <= n - 1)/*先考虑第二行到n-1行的情况*/ {
				for (j = 1; j <= right; j++) {
					if (j == 1 || j == right)
						printf("*");
					else
						printf(" ");
				}
				printf("\n");/*打印完一行换行*/
			}
			else /*考虑第一行和第n行的情况*/ {
				for (j = 1; j <= right; j++) {
					if (j % 2 != 0) 	printf("*");
					else				printf(" ");
				}
				printf("\n");
			}
		}
	}
	
	return 0;
}