Tree

PROGRAM Tree (Input, Output);
{Written by Jason John Schwarz with Turbo Pascal v6.0.
Purpose: A demonstration binary tree.}

USES CRT;

TYPE
Point = ^Node;
Node = RECORD
Data : REAL;
Left : Point;
Right : Point;
END;{Node}

VAR
Root : Point;

PROCEDURE Initialize;
BEGIN
Root:=NIL;
END;{Initialize}

PROCEDURE Create (Data : REAL);
BEGIN
NEW(Root);
Root^.Data:=Data;
Root^.Left:=NIL;
Root^.Right:=NIL;
END;{Create}

PROCEDURE AddNode (Data :REAL; Root : Point);
VAR
Temp : Point;
BEGIN
NEW(Temp);
IF Data>=Root^.Data THEN Root^.Right:=Temp;
IF Data=Root^.Data) THEN
IF Root^.Right<>NIL THEN Add(Data,Root^.Right)
ELSE AddNode(Data,Root);
IF (Data<>NIL THEN Add(Data,Root^.Left)
ELSE AddNode(Data,Root);
END;{Root=NIL}
END;{Add}

PROCEDURE InOrder (Root : Point);
BEGIN
IF Root <> NIL THEN BEGIN
InOrder(Root^.Left);
WRITELN(Root^.Data);
InOrder(Root^.Right);
END;{Root<>NIL}
END;{InOrder}

PROCEDURE PreOrder (Root : Point);
BEGIN
IF Root <> NIL THEN BEGIN
WRITELN(Root^.Data);
PreOrder(Root^.Left);
PreOrder(Root^.Right);
END;{Root<>NIL}
END;{PreOrder}

PROCEDURE PostOrder (Root : Point);
BEGIN
IF Root<>NIL THEN BEGIN
PostOrder(Root^.Left);
PostOrder(Root^.Right);
WRITELN(Root^.Data);
END;{Root<>NIL}
END;{PostOrder}

PROCEDURE GetData;
VAR Data : REAL;
BEGIN
WRITE(Output,'What is the new number?');
READLN(Input,Data);
Add(Data,Root);
END;{GetData}

PROCEDURE Loop;
VAR
Choice : CHAR;
BEGIN
REPEAT
Choice:=CHR(0);
GetData;
CLRSCR;
WRITELN(Output,'InOrder Tree:');
InOrder(Root);
WRITELN(Output,'PostOrder Tree:');
PostOrder(Root);
WRITELN(Output,'PreOrder Tree:');
PreOrder(Root);
WRITE(Output,'Do you wish to add another number?');
READLN(Input,Choice);
UNTIL Choice IN ['N','n'];
END;{Loop}

BEGIN
Initialize;
Loop;
END.