Drawing a chessboard with Turtle (even number dimension fail)

Question

I have written this Python code with turtle graphics for drawing a chessboard by given dimension. The problem I'm facing is when I enter an odd number everything works just fine:

• The last square is also filled, I just didn't manage to screen shot it on time

But when I enter an even number, it's like:

Here's the code:

from turtle import *
import sys


def main():
    dimension = int(input('Enter dimension: '))
    side = 50

    x_coord = -250
    y_coord = 300

    turtle = Turtle()
    turtle.speed('fastest')
    turtle.pensize(5)

    for i in range(dimension ** 2):
        if not i % dimension:
            y_coord -= side
            turtle.penup()
            turtle.setx(x_coord)
            turtle.sety(y_coord)
            turtle.pendown()

        if not i % 2:
            turtle.begin_fill()

        for _ in range(4):
            turtle.forward(side)
            turtle.right(90)

        turtle.forward(side)
        turtle.end_fill()


if __name__ == '__main__':
    sys.exit(main())

Answer 1

A similar flag-based solution with alternate approaches. I don't understand what your main() layout gets you so I reworked it to be a potential library with the test code under __main__:

import turtle

def draw_board(dimension, x_coord, y_coord, side):

    parity = False

    for i in range(dimension ** 2):
        if i % dimension == 0:
            y_coord -= side
            turtle.penup()
            turtle.setpos(x_coord, y_coord)
            turtle.pendown()
            parity = parity != (dimension % 2 == 0)  # logical XOR

        if parity:
            turtle.begin_fill()

        for _ in range(4):
            turtle.forward(side)
            turtle.right(90)

        if turtle.filling():
            turtle.end_fill()

        turtle.forward(side)

        parity = not parity


if __name__ == '__main__':
    size = int(input('Enter dimension: '))

    turtle.speed('fastest')

    turtle.pensize(5)

    draw_board(size, -250, 300, 50)

    turtle.hideturtle()

    turtle.exitonclick()