type 'a avl = Vide | N of int * 'a avl * 'a * 'a avl ;;

let exemple_1 =
 N
  (3, N (1, N (0, Vide, 0, Vide), 1, N (0, Vide, 2, Vide)), 3,
   N
    (2, N (1, N (0, Vide, 4, Vide), 5, N (0, Vide, 6, Vide)), 7,
     N (1, N (0, Vide, 8, Vide), 9, N (0, Vide, 10, Vide))))
and  exemple_2 =
 N
  (4, N (0, Vide, 0, Vide), 1,
   N
    (3, N (0, Vide, 2, Vide), 3,
     N
      (2, N (1, N (0, Vide, 4, Vide), 5, N (0, Vide, 6, Vide)), 7,
       N (1, N (0, Vide, 8, Vide), 9, N (0, Vide, 10, Vide)))))
and exemple_3 =
 N
  (2, N (1, N (0, Vide, 0, Vide), 1, N (0, Vide, 2, Vide)), 3,
   N
    (2, N (1, N (0, Vide, 4, Vide), 5, N (0, Vide, 6, Vide)), 7,
     N (1, N (0, Vide, 8, Vide), 9, N (0, Vide, 10, Vide))))
;;

(* Script de la question 12: *)

(* let b=ref true ;;
 * let a=ref Vide ;;
 * for i=0 to 100 do
 *   a:= inserer !a i ;
 *   b:= !b && check_avl !a && check_abr !a
 * done ;
 * for i=0 to 100 do
 *   a:= supprimer !a i ;
 *   b:= !b && check_avl !a && check_abr !a
 * done ;
 * !b ;; *)