HollowDiamond_Pattern.c

#include <stdio.h>

void printHollowDiamond(int n) {
    int i, j;
    for (i = 1; i <= n; i++) {
        for (j = i; j < n; j++) {
            printf(" ");
        }
        for (j = 1; j <= (2 * i - 1); j++) {
            if (j == 1 || j == (2 * i - 1)) {
                printf("*");
            } else {
                printf(" ");
            }
        }
        printf("\n");
    }
    for (i = n - 1; i >= 1; i--) {
        for (j = n; j > i; j--) {
            printf(" ");
        }
        for (j = 1; j <= (2 * i - 1); j++) {
            if (j == 1 || j == (2 * i - 1)) {
                printf("*");
            } else {
                printf(" ");
            }
        }
        printf("\n");
    }
}

int main() {
    int n;
    scanf("%d", &n);
    printHollowDiamond(n);
    return 0;
}

/*
for n = 5 

    *
   * *
  *   *
 *     *
*       *
 *     *
  *   *
   * *
    *

*/