#TJHSST ~ Random Walks

rndwalk2.c

/*
  Random Walks
*/
#include "stdio.h"
#include "stdlib.h"
#include "time.h"
#include "conio.h"
#include "graphics.h"

#define MAXX 40
#define MAXY 40
#define EMPTY 0
#define OCCUPIED 1

#define direction (random(3)-1)
#define magnitude 1
#define outside(x,y) ((x>=(MAXX-1))||(x<1)||(y>=(MAXY-1))||(y<1))

char matrix[MAXY][MAXX];

void ginit(void)
{
  int gdriver,gmode;

  gdriver=CGA;
  gmode=CGA;
  initgraph(&gdriver,&gmode,"");
}

int start(x,y)
int *x,*y;
{
  switch(random(100)%4)  {
    case 0 :
      *x=1;
      *y=random(MAXY-2)+1;
      break;
    case 1 :
      *x=random(MAXX-2)+1;
      *y=1;
      break;
    case 2 :
      *x=MAXX-2;
      *y=random(MAXY-2)+1;
      break;
    case 3 :
      *x=random(MAXX-2)+1;
      *y=MAXY-2;
      break;
  }
}

int touched(x,y)
int x,y;
{
  int sx,sy;

  for(sy=(-1);sy<2;sy++)
    for(sx=(-1);sx<2;sx++)
      if(matrix[y+sy][x+sx]==OCCUPIED)
	return 1;
  return 0;
}

int main()
{
  int x,y,out;

  ginit();
  cleardevice();
  for(y=0;y<MAXY;y++)
    for(x=0;x<MAXX;x++)
      matrix[y][x]=EMPTY;
  matrix[MAXY/2][MAXX/2]=OCCUPIED;
  putpixel(MAXX/2,MAXY/2,2);
  randomize();
  while(!kbhit())  {
    start(&x,&y);
    out=outside(x,y);
    while(!touched(x,y)&&!out&&!kbhit())  {
      x+=direction*magnitude;
      y+=direction*magnitude;
      out=outside(x,y);
    }
    if(!out)  {
      matrix[y][x]=OCCUPIED;
      putpixel(x,y,2);
    }
  }
}

rndwalk3.c

/*
  Random Walks
*/
#include "stdio.h"
#include "string.h"
#include "sys/time.h"

#define MAXX 100
#define MAXY 100

#define EMPTY 0
#define OCCUPIED 1

#define direction (random(3)-1)
#define outside(x,y) ((x>=(MAXX-1))||(x<1)||(y>=(MAXY-1))||(y<1))

char matrix[MAXY][MAXX];

int start(x,y)
int *x,*y;
{
  switch(random()&3)  {
    case 0 :
      *x=1;
      *y=random()%(MAXY-2)+1;
      break;
    case 1 :
      *x=random()%(MAXX-2)+1;
      *y=1;
      break;
    case 2 :
      *x=MAXX-2;
      *y=random()%(MAXY-2)+1;
      break;
    case 3 :
      *x=random()%(MAXX-2)+1;
      *y=MAXY-2;
      break;
  }
}

int touched(x,y)
int x,y;
{
  int sx,sy;

  for(sy=(-1);sy<2;sy++)
    for(sx=(-1);sx<2;sx++)
      if(matrix[y+sy][x+sx]==OCCUPIED)
	return 1;
  return 0;
}

int main(argc,argv)
int argc;
char *argv[];
{
  int x,y,out,count;
  FILE *outfile;
  char filename[80]

  strcpy(filename,argv[1]);
  for(y=0;y<MAXY;y++)
    for(x=0;x<MAXX;x++)
      matrix[y][x]=EMPTY;
  matrix[MAXY/2][MAXX/2]=OCCUPIED;
  count=1;
  srandom(time(0));
  while(!kbhit()&&count<MAXATOMS)  {
    start(&x,&y);
    out=outside(x,y);
    while(!touched(x,y)&&!out&&!kbhit())  {
      x+=direction;
      y+=direction;
      out=outside(x,y);
    }
    if(!out)  {
      matrix[y][x]=OCCUPIED;
      count++;
    }
  }
  outfile=fopen(filename,"w");
  for(y=0;y<MAXY;y++)
    for(x=0;x<MAXX;x++)
      if(matrix[y][x]==OCCUPIED)
	fprintf(outfile,"%d %d\n",x,y);
  fclose(outfile);
}