Turn-exercise-065-into-practice

practice/065/answer/impl.ml

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+type 'a binary_tree =
+  | Empty
+  | Node of 'a * 'a binary_tree * 'a binary_tree
+
+let layout_binary_tree_2 t =
+    let rec height = function
+      | Empty -> 0
+      | Node (_, l, r) -> 1 + max (height l) (height r) in
+    let tree_height = height t in
+    let rec find_missing_left depth = function
+      | Empty -> tree_height - depth
+      | Node (_, l, _) -> find_missing_left (depth + 1) l in
+    let translate_dst = 1 lsl (find_missing_left 0 t) - 1 in
+                        (* remember than 1 lsl a = 2ᵃ *)
+    let rec layout depth x_root = function
+      | Empty -> Empty
+      | Node (x, l, r) ->
+         let spacing = 1 lsl (tree_height - depth - 1) in
+         let l' = layout (depth + 1) (x_root - spacing) l
+         and r' = layout (depth + 1) (x_root + spacing) r in
+           Node((x, x_root, depth), l',r') in
+    layout 1 ((1 lsl (tree_height - 1)) - translate_dst) t
+

practice/065/answer/test/dune

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+(include_subdirs no)
+(test (name run) (libraries ounit2 ex))

practice/065/answer/test/run.ml

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+module Test = Ex.Make(Ex.Answer)
+
+let () = OUnit2.run_test_tt_main Test.v

practice/065/dune

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+(include_subdirs qualified)
+(library (name ex) (libraries ounit2))

practice/065/dune-project

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+(lang dune 3.7)

practice/065/ex.ml

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+open OUnit2
+
+module type Testable = sig
+  type 'a binary_tree = | Empty | Node of 'a * 'a binary_tree * 'a binary_tree
+  val layout_binary_tree_2 : 'a binary_tree -> ('a * int * int) binary_tree
+end
+
+module Make(Tested: Testable) : sig val v : OUnit2.test end = struct
+  open Tested
+
+  let v = "layout_binary_tree_2" >::: [
+    "test_layout_binary_tree_2_works_correctly" >:: (fun _ ->
+        let example_layout_tree =
+          Node ('a', Node ('b', Empty, Empty), Node ('c', Empty, Empty)) in
+        let expected_layout =
+          Node (('a', 2, 1), Node (('b', 1, 2), Empty, Empty), Node (('c', 3, 2), Empty, Empty)) in
+        assert_equal expected_layout (layout_binary_tree_2 example_layout_tree));
+  ]
+end
+
+module Work : Testable = Work.Impl
+
+module Answer : Testable = Answer.Impl

practice/065/work/impl.ml

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+type 'a binary_tree =
+  | Empty
+  | Node of 'a * 'a binary_tree * 'a binary_tree
+
+let layout_binary_tree_2 _ = failwith "Not yet implemented"

practice/065/work/test/dune

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+(include_subdirs no)
+(test (name run) (libraries ounit2 ex))

practice/065/work/test/run.ml

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+module Test = Ex.Make(Ex.Work)
+
+let () = OUnit2.run_test_tt_main Test.v