laba_2_1_delphi

Program Project1;
Uses
  System.SysUtils;
Var
    ArrX, ArrY : Array of Real;
    I, N, J : Integer;
    X, Y : Real;
    Iscorrect, GotInto : Boolean;
Const
    Min = 3;
Begin
    Writeln ('The polygon is given by the coordinates of its vertices. Determine if the given point belongs to the area of the polygon.');
    Writeln ('Input number of vertices:');
    Repeat
        Iscorrect := True;
        Try
            Readln (N);
        Except
            Writeln ('Please, enter a positive integer number:');
            IsCorrect := False;
        End;
        If (IsCorrect And (N < Min)) Then
        Begin
            Writeln('There must be more than 2 vertices.');
            IsCorrect := False;
        End;
    Until (Iscorrect);
    SetLength (ArrX, N);
    SetLength (ArrY, N);
    Dec (N);
    For I := 0 To N Do
        Begin
            Writeln ('Enter coordinates for point ', I + 1, ':');
            Repeat
                Iscorrect := True;
                Try
                    Readln (ArrX[I]);
                Except
                    Writeln ('Please, enter a number:');
                    IsCorrect := False;
                End;
            Until (Iscorrect);
            Repeat
                Iscorrect := True;
                Try
                    Readln (ArrY[I]);
                Except
                    Writeln ('Please, enter a number:');
                    IsCorrect := False;
                End;
            Until (Iscorrect);
        End;

    Writeln ('Input point coordinates:');
    Repeat
        Iscorrect := True;
            Try
                Readln (X);
            Except
                Writeln ('Please, enter a number:');
                IsCorrect := False;
            End;
    Until (Iscorrect);
    Repeat
         Iscorrect := True;
            Try
                Readln (Y);
            Except
                Writeln ('Please, enter a number:');
                IsCorrect := False;
            End;
    Until (Iscorrect);
    GotInto := False;
    Inc (N);
    J := N - 1;
    For I := 0 To N Do
        Begin
            If ((((ArrY[I] <= Y) and (Y <= ArrY[J])) or ((ArrY[J] <= Y) and (Y <= ArrY[I]))) and (((ArrY[J] - ArrY[I]) <> 0) and
            (X >= ((ArrX[J] - ArrX[I]) * (Y - ArrY[I]) / (ArrY[J] - ArrY[I]) + ArrX[I])))) then
                GotInto := Not (GotInto);
            Inc (J);
            If (J = N) then
                J := 0;
        End;
    If (GotInto) then
        Writeln ('Point belongs to area!')
    Else
        Writeln ('Point does not belong to area.');
    Readln;
End.