题解 | #空心正方形图案#

#include<stdio.h>
int main() {
    int num = 0;
    int h = 0;
    int l = 0;
    char arr[20][20];
    while (scanf("%d", &num) != EOF) {
        for (h = 0; h < num; h++) {
            for (l = 0; l < 2 * num - 1; l++) {
                if (h == 0 && l % 2 == 0 || h == num - 1 && l % 2 == 0 || l == 0 ||
                        l == 2 * num - 2) {
                    arr[h][l] = '*';
                } else {
                    arr[h][l] = ' ';
                }
                printf("%c", arr[h][l]);
            }
            printf("\n");
        }
    }
    return 0;
}