Вопросы к экзамену с ответами и демо-программами на Паскале / ex18_1

program GalkaVV;
uses crt;
type
TText=text;
PListItem=^TListItem;
TListItem=record
Data:string;
Next:PListItem;
end;

PFIFO=^TFIFO;
TFIFO=object
private
AList,BList:PListItem;
public
constructor Init;
destructor Done;
procedure Put(Element: string);
function Get:string;
function NotEmpty:boolean;
end;

constructor TFIFO.Init;
begin
AList:=Nil;
BList:=Nil;
end;

destructor TFIFO.Done;
var
P:PListItem;
begin

while AList<>Nil do
begin
P:=AList^.Next;
Dispose(AList);
AList:=P;
end;
end;


function TFIFO.Get:string;
var
P:PListItem;
GetData: string;
begin
if AList=Nil then begin Get:=''; exit; end;
P:=AList^.Next;
GetData:=AList^.Data;
Dispose(AList);
AList:=P;
if AList=nil then BList:=AList;
Get:=GetData;
end;

Procedure TFIFO.Put(Element: string);
var
P: PListItem;
begin
New(P);
P^.Data:=Element;
if (BList=nil) and (AList=nil) then
begin
P^.Next:=nil;
AList:=P;
BList:=P;
end
else
begin
BList^.Next:=P;
P^.Next:=nil;
BList:=P;
end;
end;

function TFIFO.NotEmpty;
begin
NotEmpty:=AList<>nil;
end;

procedure ShowFile(f1:string);
var
inF: TText;
Str: string;
begin
assign(inF,f1);
{$I-}
reset(inF);
if ioresult<>0 then begin write('File not found!'); exit; end;
{$I+}
while not EOF(inF) do
begin
readln(inF,str);
writeln ('1: ',str);
end;
close(inF);
end;


Procedure Sort(var f1:string);
var
inF: TText;
Str,max,StrTmp:string;
SortList,SortListTmp:TFIFO;
imax,j,i: Longint;
Tmp:PListItem;
begin
imax:=0;
SortList.init;
SortListTmp.init;
assign(inF,f1);
{$I-}
reset(inF);
if ioresult<>0 then begin write('File not found!'); exit; end;
{$I+}
while not EOF(inF) do
begin
readln(inF,Str);
SortList.Put(Str);
inc(imax);
end;
if SortList.AList=nil then exit;
for i:=1 to imax do
begin
max:=SortList.Get;
Tmp:=SortList.AList;
for j:=i to imax do
begin
if Tmp^.Data>max then
begin
StrTmp:=max;
max:=Tmp^.Data;
Tmp^.Data:=StrTmp;
Tmp:=Tmp^.Next;
end
else Tmp:=Tmp^.Next;
end;
SortListTmp.Put(max);
end;
{$I-} {
reWrite(inF);
if ioresult<>0 then begin write('Can not create file!'); exit; end;
{$I+}
for i:=1 to imax do writeln(SortListTmp.Get);
{close(inF);}
SortList.Done;
SortListTmp.Done;
end;

var
List:TFIFO;
i:byte;
a:string;

begin
clrscr;
a:='ex1801.txt';
List.init;
Sort(a);
{ ShowFile(a);}
List.Done;
end.