size=301;
ar=zeros(size+2,size+2);
ar(size,:)=100*ones(1,size+2);
vd=1;
figure('Position',[100,100,400,400])
q=plot(size,((size+1)/2),'EraseMode','none','Color','red')
axis([0 size 0 size])
pts=0;
for i=1:100000
ch=rand(1);
x=1;
y=floor(ch*size+1);
 for j=1:10000
  xlast=x;
  ylast=y; 
  ch=rand(1);
  if (ch < .25 )
   x=x+1;
  elseif (ch >=.25 & ch < .5)
   x=x-1;
  elseif (ch >= .5 & ch < .75)
   y=y+1;
  else
   y=y-1;
  end
  if (x < 2 | y < 2 | x > size | y > size)
   break
  end
  if (ar(x,y) == 100 | ar(x,y+1) == 100 | ar(x,y-1) == 100)
   ar(x-1,ylast)=100;
   pts=pts+1;
   [i,pts]
   set(q,'XData',x-1,'YData',ylast)
   drawnow
   break
  end
  x=x+vd;
  if (x < 2 | y < 2 | x > size | y > size)
   break
  end
  if (ar(x,y) == 100 | ar(x,y+1) == 100 | ar(x,y-1) == 100)
   ar(x-1,ylast)=100;
   pts=pts+1;
   [i,pts]
   set(q,'XData',x-1,'YData',ylast)
   drawnow
   break
  end
 end
end