Random.int 7;;

let palindrome u = 
let l = ref [] in
for i = 0 to (String.length u -1) do 
l:=u.[i]::!l done;
!l = List.rev !l;;

palindrome "radrr";;

let nb_palindrome u =
	let n =String.length u in 
	let nb = ref 0 in
	for i = 0 to (n-1) do
	for j = (1+i) to n do 
	if palindrome (String.sub u i (j-i)) then nb:=!nb+1
done done;!nb;;

nb_palindrome "babb";;

let nb_palindrome_bis u =
	let n =String.length u in 
	let l =ref[] in
	for i = 0 to (n-1) do
	for j = (1+i) to n do 
	if palindrome (String.sub u i (j-i)) then l := (String.sub u i (j-i))::!l
done done;!l;;

nb_palindrome_bis "babb";;

let matrice u = 
	let n = String.length u in
	let m =Array.make_matrix (n+1) (n+1) false in 
	for i=0 to (n-1) do m.(i).(i+1) <-true 
	done;
	for i = 0 to (n-2) do
		m.(i).(i+2)<- u.[i]=u.[i+1]
	done;
	for j = 3 to n do 
	for i = 0 to (j-3) do   
		m.(i).(j)<- (m.(i+1).(j-1)&&(u.[i]=u.[j-1]))
		done done ; m;;
matrice "kayak";;



let nb_palindrome2 u =
	let m =matrice u in 
	let n=Array.length m in
	let nb = ref 0 in 
	for i = 0 to (n-1) do
	for j = i+1 to (n-1) do
		if m.(i).(j) then nb := !nb +1
		done;done;!nb;;
nb_palindrome2 "kayak";;

let sous_palindrome2 u =
	let m = matrice  u in
	let n  = Array.length m in 
	let l= ref [] in 
	for i = 0 to (n-1) do 
	for j = i+1 to (n-1) do
	if m.(i).(j) then
		l := (String.sub u i (j-i))::!l
	done;done;!l;;

sous_palindrome2 "kayak";;