laba 9

program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

type ph=^a;
     a=record
     f,b:ph;
     n:real;
     end;

 var first,next,prev,last:ph;
     i,k:integer;
begin
  write('Enter number of elements in list: ');
  readln(k);
  new(first); //declaration of first el of list
  next:=first;
  writeln('Enter elements');
  //entering list
  for i := 1 to k do begin
    readln(next^.n);
    new(next^.f);
    prev:=next;
    next:=next^.f;
    next^.b:=prev;
  end;

  //delete last empty element
  last:=next;
  next:=prev;
  dispose(last);

  //move to the first el of list
  next:=first;

  writeln('Wanted sums:');
  for i := 1 to k do begin
    writeln((next^.n)+(prev^.n):0:3);
    next:=next^.f;
    prev:=prev^.b;
  end;
  readln;
end.