library(Rlab)
set.seed(9999)    
m=10000;
n=100;
p=0.2 # proba la grenouille saute d'une marche
minEndMarches = 1e10
pro<-array(0,2*n);
for (j in 1:m){
  marches<-c(0);
  pos=0;
  tirage<-rbern(n,prob=p);
for (i in 1:n) {
  tir=tirage[i];
  saut=2;
  if (tir==1) {saut=1;}
  pos=pos+saut;
  pro[pos]=pro[pos]+1;
  marches<-c(marches,pos)
}
  if(pos<minEndMarches){minEndMarches=pos;}
}
cat('longueur =',length(pro))
cat('constante limite =',1./(2.-p));

# pdf(file = "ex7ftd5SimuQ2.pdf",   # The directory you want to save the file in
#     width = 4, # The width of the plot in inches
#     height = 4) # The height of the plot in inches
# plot(1:minEndMarches,pro[1:minEndMarches]/m);
# abline(h=1./(2.-p))
# dev.off()
#curve(f,1:(2*n),xname="marches");