Optimize hollow diamond pattern printing in c with minimum loops

Am trying to print hollow diamond pattern with * outline with minimum loops. I optimized with 2 loops. Is there any other way to still optimize this code
My output using 2 loops

void main()
{
        int row,col,n,k;

        printf("Enter no of rows: ");
        scanf("%d",&n);

        for(row=0, k=1; row<=2*n; row>n?k++:k, printf("\n"), row++)
                for(col=-n; col<=n; col++)
                        (col>0?col:-col) < (row<=n?row:(row-2*k)) ? printf(" ") : printf("*");
}