Vector realization

(*
    Реализация
    Конструктив
    Хэши
    ДП
    Графы
    События
    Строки
*)

(*
    Capacity = кол-во элементов, которые мы можем сохранить
    Size = кол-во элементов в списке
    xxxxxxxxxxxxxxxx

*)
Const
    InitialCapacity = 2;

Type
    TElem = LongInt;
    PElem = ^TElem;

    TArray = Array Of Telem;
    PArray = ^TArray;

    TVector = Record
        Size, Capacity : LongInt;
        Ptr : PArray;
    End;

Procedure InitVector(Var V : TVector);
Begin
    V.Size := 0;
    V.Capacity := InitialCapacity;
    GetMem(V.Ptr, SizeOf(TElem) * InitialCapacity);
End;

Function Get(Var V : TVector; Pos : LongInt) : PElem;
Var
    Res : Pointer;
Begin
    Res := V.Ptr;
    Inc(Res, Pos * SizeOf(TElem));
    Get := Res;
End;

Function Pop(Var V : TVector) : PElem;
Begin
    Dec(V.Size);
    Pop := Get(V, V.Size);
End;

Procedure PushBack(Var V : TVector; X : TElem);
Begin
    If V.Size + 1 < V.Capacity Then
    Begin
        Get(V, V.Size)^ := X;
        Inc(V.Size);
    End Else
    Begin
        Inc(V.Capacity, V.Capacity);
        ReAllocMem(V.Ptr, V.Capacity * SizeOf(TElem));
        PushBack(V, X);
    End;
End;

Var
    V : TVector;
    I, X : LongInt;
Begin
    InitVector(V);
    Read(I);
    For I := 1 To I Do
    Begin
        Read(X);
        PushBack(V, X);
    End;
    For I := 0 To V.Size - 1 Do
        WriteLn(Get(V, I)^);
    WriteLn('Before pop:');
    WriteLn(V.Capacity, ' ', V.Size);
    While V.Size <> 0 Do Pop(V);
    WriteLn('After pop:');
    WriteLn(V.Capacity, ' ', V.Size);
End.