%%%%%%%%%%%% CORRIGE FOURMI DE LANGTON %%%%%%%%%%%%%%

clear all
clf
global N
N=80;
m=zeros(N,N);
for i=1:N
   for j=1:N
      affiche_cellule(i,j,'g')
   end
end
fi=round(N/2);
fj=fi;
fd=0;
affiche_cellule(fi,fj,'r')
axis equal
axis off
drawnow
hold on
cpt=0;
ok=1;
while ok
   [m,fi,fj,fd,ok]=deplacement(m,fi,fj,fd);
   cpt=cpt+1;
end
cpt

function affiche_cellule(i,j,couleur)
rectangle('Position',[i,j,1,1],'facecolor',couleur,'EraseMode','none')
line([i,i+1],[j,j],'color',couleur,'EraseMode','none')
line([i,i+1],[j+1,j+1],'color',couleur,'EraseMode','none')
line([i,i],[j,j+1],'color',couleur,'EraseMode','none')
line([i+1,i+1],[j,j+1],'color',couleur,'EraseMode','none')

function [m,fi,fj,fd,ok]=deplacement(m,fi,fj,fd)
ok=1;
m(fi,fj)=1-m(fi,fj);
if m(fi,fj)==0
   coul='g';
else
   coul='b';
end
affiche_cellule(fi,fj,coul);
switch fd
case 0
   fi=fi+1;
case 1
   fj=fj+1;
case 2
   fi=fi-1;
case 3
   fj=fj-1;
end
if valide(fi,fj)
   if m(fi,fj)==0
      fd=mod(fd-1,4);
   else
      fd=mod(fd+1,4);
   end
   affiche_cellule(fi,fj,'r')
else
   ok=0;
end

function oui=valide(i,j)
oui = i>=1 & i<=N & j>=1 & j<=N;


%%%%%%%%%%%%%% CORRIGE PERCOLATION %%%%%%%%%%%%

clear all
rand('state',sum(100*clock));
global n M f
n=80;
M=zeros(n,n);
M(ceil(n/2),ceil(n/2))=1;
fin=false;
affiche2;
while ~fin
    propagation;
    affiche2;
    fin=test2;
end

function affiche2()
global M
clf
spy(M==0,'b');
hold on
spy(M==2,'k');
drawnow

function propagation()
global M n
seuil=0.5;
T=M;
for i=1:n
    for j=1:n
        if T(i,j)==1
            feu(i,j,i-1,j,T);
            feu(i,j,i,j+1,T);
            feu(i,j,i+1,j,T);
            feu(i,j,i,j-1,T);
            M(i,j)=2;
        end
    end
end

function feu(i,j,ii,jj,T)
global M
seuil=0.5;
if valide(ii,jj) & T(ii,jj)==0 & rand<seuil
    M(ii,jj)=1;
end

function ok=valide(i,j)
global n
ok = i>=1 & i<=n & j>=1 & j<=n;

function ok=test2()
global M
ok=sum(sum(M==1))==0;