(*  Exercice 1  *)

let pile = Stack.create ();;


Stack.push 17 pile;;

Stack.pop pile ;;

let tete pile =
	if Stack.is_empty pile then failwith "pile vide"
	else
		begin
			let a = Stack.pop pile in
			Stack.push a pile ;
			a
		end;;

tete pile;;

let creation_pile liste =
	let ma_pile = Stack.create () in
	let rec aux liste =
		match liste with
			| [] -> ma_pile
			| a::reste ->
					begin
						Stack.push a ma_pile ;
						aux reste
					end
	
	
	
	in
	aux liste	;;
	
	
let pile_2 = creation_pile [1;2;3;4;5];;

tete pile_2;;

Stack.pop pile_2;;


let taille pile =
	let pile_stock = Stack.create () in
	let rec compte pile nb =
		if Stack.is_empty pile then nb
			else 
				begin
					let sommet = Stack.pop pile in
					Stack.push sommet pile_stock ;
					compte pile (nb+1)				
				end	
			in
		
	let nb = compte pile 0 in
	let rec reconstruit () =
			if Stack.is_empty pile_stock then ()
			else 
				begin
					Stack.push ( Stack.pop pile_stock ) pile ;
					reconstruit () ; 
				end	
	in
	reconstruit () ;
	nb;;





(*  Exercice 3  *)

let associe k_1 k_2 =
	(k_1 = '(' && k_2 = ')' )
		||
	(k_1 = '[' && k_2 = ']' )
	||
	(k_1 = '{' && k_2 = '}' );;

associe '{' '}';;

let ouvrante = ['[' ; '(' ; '{' ];;
let fermante = [ ']' ; ')' ; '}'];;

let bon_parenthesage phrase =
	let pile_stock = Stack.create () in
	let booleen = ref true in
	let indice = ref 0 in
	let taille = String.length phrase in
	while ( !indice < taille ) && !booleen do
		let lettre = phrase.[ !indice] in
			if List.mem lettre ouvrante then Stack.push lettre pile_stock ;
			if List.mem lettre fermante then 
				 begin
				 	if Stack.is_empty pile_stock then booleen := false
				 	else
				 	let k = Stack.pop pile_stock in
				 	booleen := associe k lettre ;
				 end ;
			incr indice ;	
	done;
	Stack.is_empty pile_stock && !booleen ;;


let phrase_exemple ="(1+2[x+2] -3 {5x+3})";;
bon_parenthesage phrase_exemple ;;


let phrase_exemple_2 ="(1+2[x+{ 2] -5x+3})";;
bon_parenthesage phrase_exemple_2;;