unit MyQueue;

interface

type
 TList = ^TElem;
 TElem = record
             INFO: char;
             NEXT : TList
            end;

 TQueue = class
            private
              head:TList;
              tail:TList;
            public
              procedure Init (var Q:TQueue);
              Function Empty(Q:TQueue):boolean;
              Procedure Push(var q:TQueue; e:Char);
              Function Pop(var q:TQueue):Char;
          end;

implementation

 procedure TQueue.Init (var Q:TQueue);
 begin
  q.head:=nil
 end;

 Function TQueue.Empty(Q:TQueue):boolean;
 begin
  Empty:=(q.head=nil)
 end;

 Procedure TQueue.Push(var q:TQueue; e: Char);
 var z:Tlist;
 begin
  new(z);
  z^.info:=E;
  z^.next:=nil;
  If Empty(q) then q.head:=z else q.tail^.next:=z;
  q.tail:=z
 end;

 Function TQueue.Pop(var q:TQueue):Char;
 var
  z:TList;
 begin
  z:=q.head;
  q.head:=z^.next;
  Pop:=Z^.info;
  dispose(z)
 end;

end.