unit uAlgo;

interface

type
   PNode = ^TNode;
   TNode = record
      Left: PNode;
      Right: PNode;
      Key: Byte;
   end;

function Add(Node: PNode; Key: Byte): PNode;
function Remove(Node: PNode; Key: Byte): PNode;
external 'RemoveAlgo.dll' name 'Remove';
function MaxDepth(Node: PNode): Byte;
function Exists(Node: PNode; Key: Byte): Boolean;
procedure DeleteAll(var Node: PNode);

implementation

procedure DeleteAll(var Node: PNode);
begin
   if Node <> nil then
   begin
      DeleteAll(Node.Left);
      DeleteAll(Node.Right);
      Dispose(Node);
   end;
end;

function MaxDepth(Node: PNode): Byte;
var
   LeftDepth, RightDepth: Byte;
begin
   if Node = nil then
      MaxDepth := 0
   else
   begin
      LeftDepth := MaxDepth(Node.Left);
      RightDepth := MaxDepth(Node.Right);
      if LeftDepth > RightDepth then
         MaxDepth := LeftDepth + 1
      else
         MaxDepth := RightDepth + 1;
   end;
end;

function Add(Node: PNode; Key: Byte): PNode;
begin
   if Node = nil then
   begin
      New(Node);
      Node.Left := nil;
      Node.Right := nil;
      Node.Key := Key;
      Add := Node;
   end
   else
      if Key > Node.Key then
         Node.Right := Add(Node.Right, Key)
      else
         if Key < Node.Key then
            Node.Left := Add(Node.Left, Key);
   Add := Node;
end;

function Exists(Node: PNode; Key: Byte): Boolean;
begin
   if (Node <> nil) and ((Node.Key = Key) or
     (Exists(Node.Right, Key)) or (Exists(Node.Left, Key))) then
      Exists := True
   else
      Exists := False;
end;

end.