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/**************************************************************************
randomlist.cpp - Some "random functions" :-)
Copyright (C) 1997,98 Antonio Larrosa Jimenez
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Send comments and bug fixes to larrosa@kde.org
or to Antonio Larrosa, Rio Arnoya, 10 5B, 29006 Malaga, Spain
***************************************************************************/
#include "randomlist.h"
#include <stdlib.h>
#include <stdio.h>
#define RAND_UNIFORM (double)rand()/(double)RAND_MAX
int random_discrete(double *distrib,int n)
{
int i=0;
double g=0.0;
double z=0.0;
while ((z==0.0)||(z==1.0)) z=RAND_UNIFORM;
while ((g<z)&&(i<n))
{
g+=distrib[i];
i++;
};
return i-1;
}
double *generate_discrete_uniform_distrib(int n)
{
double *distrib=new double[n];
for (int i=0;i<n;i++)
distrib[i]=1.0/(double)n;
return distrib;
}
void remove_lmn_from_discrete_distrib(int k,double *distrib,int n,int used=0)
{
int i;
if (used==0) //guess how many values of the v.a. are strictly positive
{
for (i=0;i<n;i++) if (distrib[i]>0) used++;
};
used--; // k will no longer be used :-)
if (used==0) return;
double piece=distrib[k]/(double)used;
distrib[k]=0.0;
for (i=0;i<n;i++) if (distrib[i]>0) distrib[i]+=piece;
}
void show_distrib(double *distrib,int n)
{
printf("(");
for (int j=0;j<n;j++) printf("%g,",distrib[j]);
printf(")\n");
}
int *generate_random_list(int n)
{
if (n==0) return NULL;
int *list=new int[n];
double *distrib=generate_discrete_uniform_distrib(n);
int used=n;
int x;
int i=1;
while (used>0)
{
x=random_discrete(distrib,n);
list[x]=i;
i++;
remove_lmn_from_discrete_distrib(x,distrib,n,used);
used--;
};
delete distrib;
return list;
}
int *generate_list(int n)
{
int *list=new int[n];
for (int i=0;i<n;i++)
list[i]=i+1;
return list;
}
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