/*
** 	This program calculates a solution to the eight queens problem.
** 	The code below was written to help demonstrate the Performance
** 	Coverage analyzer; it was not intended to be a slick solution.
*/

#include <stdio.h>

extern void setqueen();
extern void removequeen();
extern void trycol();
extern void print();



    int a[8];		/* a : array[1..8] of boolean	*/
    int b[16];		/* b : array[2..16] of boolean */
    int c[15];		/* c : array[-7..7] of boolean */
    int x[8];

main()			/* Start the eight queens problem solution. */

{

    int i;

    for (i=0; i <=7; i++)
	a[i] = 1;

    for (i=0; i <=15; i++)
	b[i] = 1;

    for (i=0; i <=14; i++)
	c[i] = 1;

    trycol( 0 );

    printf(" An eight queens solution has been found.\n");
    fflush( stdout );

}	/* End main: the eight queens problem solution. */





void trycol( j )
    int j;

{

    int m;
    int safe;

    m = -1;
    while (m++ < 7)
	{
	safe = (a[m] ==1) && (b[m + j] == 1) && (c[m - j + 7] ==1);
	if (safe)
	    {
	    setqueen(m, j);
	    x[j] = m + 1;
	    if (j < 7)
		trycol(j + 1);
	    else
		print();
	    removequeen(m, j);
	    }
	}
}	/* End trycol */



void setqueen(m, j)
    int m;
    int j;

{

    a[m] = 0;
    b[m + j] = 0;
    c[m - j + 7] = 0;

}	/* End setqueen */





void removequeen(m, j)
    int m;
    int j;

{

    a[m] = 1;
    b[m + j] = 1;
    c[m - j + 7] = 1;

}	/* End removequeen */


void print()

{

    int k;

    for (k=0; k<=7; k++)
	{
	printf(" %d", x[k]);
	}

    printf("\n");
    fflush( stdout );

}	/* End print */