1 files changed, 92 insertions, 0 deletions
diff --git a/semestr-3/pf/lista4/lista4.ml b/semestr-3/pf/lista4/lista4.ml
new file mode 100644
index 0000000..32ea4a6
--- /dev/null
+++ b/semestr-3/pf/lista4/lista4.ml
@@ -0,0 +1,92 @@
+(* Zadanie 1 *)
+
+type 'a btree = Leaf | Node of 'a btree * 'a * 'a btree
+
+let is_balanced bt = 
+  let rec check = function
+    | Leaf -> 0
+    | Node (rt, x, lt) -> 
+      let left_weight = check lt
+      in if left_weight == -1 then -1 else
+        let right_weight = check rt
+        in if right_weight == -1 then -1 else
+        if abs (left_weight - right_weight) <= 1 then left_weight + right_weight + 1 else -1
+  in if check bt == -1 then false else true
+
+let rec preorder = function
+  | Leaf -> []
+  | Node (lt, x, rt) ->
+    x :: ((preorder lt) @ (preorder rt)) 
+let bt = Node ((Node ((Node (Leaf, 3, Leaf)), 2, Leaf)), 
+               1, 
+               (Node (Node (Leaf, 5, Leaf), 4, Node (Leaf, 6, Leaf))))
+
+let reverse xs =
+  let rec iter res = function
+    | [] -> res
+    | hd :: tl -> (iter (hd :: res) tl) in
+  iter [] xs
+
+let halve xs =
+  let rec iter xs crawl sth = 
+    match crawl with
+      [] -> (sth, xs)
+    | [x] -> (sth, xs)
+    | st :: nd :: tl -> iter (List.tl xs) tl ((List.hd xs) :: sth) in
+  let sth, ndh = iter xs xs [] in
+  ((reverse sth), ndh)
+
+let rec bt_of_list = function
+  | [] -> Leaf
+  | x :: xs ->
+    let (sth, ndh) = (halve xs)
+    in Node (bt_of_list sth, x, bt_of_list ndh)
+
+
+(* Zadanie 2 *)
+
+type 'a place = PNil | Place of 'a list * 'a list
+
+let findNth xs n = 
+  let rec iter xs n = match xs, n with
+    | [], 0 -> PNil
+    | [], n -> failwith "n too big"
+    | xs, 0 -> Place ([], xs)
+    | x :: xs, n -> match (iter xs (n - 1)) with 
+      | PNil -> Place ([x], [])
+      | Place (bef, aft) -> Place (x :: bef, aft)
+  in match iter xs n with
+  | PNil -> PNil
+  | Place (bef, aft) -> Place (reverse bef, aft)
+
+let collapse = function
+  | PNil -> []
+  | Place (bef, aft) -> List.rev_append bef aft
+
+let add x = function
+  | PNil -> Place ([], [x])
+  | Place (bef, aft) -> Place (bef, x :: aft)
+
+let del = function
+  | PNil -> failwith "empty place"
+  | Place (_, []) -> failwith "nothing at this place"
+  | Place (bef, aft) -> Place (bef, List.tl aft)
+
+let next = function
+  | PNil -> failwith "empty place"
+  | Place (_, []) -> failwith "nothing next to this place"
+  | Place (bef, aft) -> let x = List.hd aft 
+    in Place (x :: bef, List.tl aft)
+
+let prev = function
+  | PNil -> failwith "empty place"
+  | Place ([], _) -> failwith "nothing next to this place"
+  | Place (bef, aft) -> let x = List.hd bef 
+    in Place (List.tl bef, x :: aft)
+
+
+(* Pierwszy element -- drzewo ukorzenione w aktualnym wierzcholku po usunieciu synow (czyli ojciec jest nowym synem) 
+   Drugi element -- prawe poddrzewo
+   Trzeci element -- lewe poddrzewo *)
+type 'a btplace = 'a btree * 'a btree * 'a btree
+