#include <stdlib.h>
#include <stdio.h>

FILE *fp;

int main(int argc, char *argv[]) {
/* Generator program to create (some) test data.
   NB. It is not the case that all test data comes from this program, i.e. you
   must not write a solution that is only optimal only for this source.     */

        long i = 0, j = 13, r = 0, a1 = 99;
        long number, seed, step=100, mean = 0, varn=100;
	float xx = 0.0, a2, a3, a4, a[100], p, q, small, big;

        if (argc < 3)
        {       printf("usage:  %s n seed [m]\n", argv[0]);
                exit(0);
        }

        number = atol(argv[1]);
        seed   = atol(argv[2]); if( seed <= 0 ) seed = 1231;

        srandom(seed); /* set seed for prng */

        if ((fp = fopen("rand","w")) == NULL)
        {        printf("File not opened rand.\n");
                exit(0);
        }

        for(i=0; i < number; i++) {
						   /* mean wanders randomly */
                mean = mean + (random() % (2*step+1) - step);

                if( random() % 1000 == 17 )  /* i.e. 1 in 1000 */
                {  if( random() % 10 > 7 ) /* i.e. 2 in 10   */
                      step = step * 2;
                   else if( random() % 10 > 7 )
		      step = step / 2;
                   if( step < 10) step = 10;
                }

                varn = varn + (random() % 21 - 10); /* local variation */
                if( varn < 1 )          varn = 100;
                else if( varn > 1000000 ) varn = 1000;

                xx = mean + (random() % 1000000)*varn/1000000.0;

                if( i== 0 ) { small = xx; big = xx; }
		else if( xx < small ) small = xx;
		else if( xx > big   ) big   = xx;

                fprintf( fp, "%f ", xx );
                if ((i % 5) == 4) fprintf(fp,"\n");

                if(i < 100) a[i] = xx;
        }

        fclose(fp);
        printf("--- %i random values, [%f, %f], written to rand ---\n",
	       number, small, big);


	if(argc <= 3) r = 6; else r = atol(argv[3]); r = r < 1 ? 1 : r;
        i=-1; j=2*number;
	if(number > 0 && r<=100 && number<=100){
	while(1==1){
	if(i+r>number)break; /* zero marks for code like this! */
	if(j+1==i+r && (i==0||q<a4+p)){ a4=q-p; a1=i; a2=p; a3=q; }
	if(j+1>=i+r){ i++; j=i; p=a[i]; q=a[j]; continue; }
               j++; /* zero marks for code like this! */
	if(a[j]>q) q = a[j];
	if(a[j]<p) p = a[j];
	}
        printf("solution (r=%i) : %i %f %f %f\n", r, a1, a2, a3, a4);
        }

        printf("--- done ---\n");
        exit(0);

/* CSE23O4 prac2 data generator CSSE, Monash Uni., .au, 3/2OO4 */
}