#include <stdio.h>
#include <string.h>
#include <math.h>

#define MAX_SPACE    \"                                        \"\\
                        \"                                        \"

static void hollow_diamond(int size);

int main()
{
    hollow_diamond(5);
    return 0;
}

static void hollow_diamond(int size)
{
    int i, j, n, c;
    char lspace[] = MAX_SPACE;    // left space
    char hollow[] = MAX_SPACE;    // inner hollow space
    char *ptr = hollow + sizeof(hollow) / sizeof(char) - 1;
    int size2 = size * 2;

    for(i = 0; i < size2 - 1; i++)
    {
        c = i / size;
        j = abs(c * size2 - i - c * 2);
        n = size - j - 1;

        lspace[n] = 0;
        printf(\"%s*\", lspace);
        if (j)
            printf(\"%s*\", ptr - j * 2 + 1);
        putchar(\'\\n\');
        lspace[n] = \' \';
    }
}

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