棋盘覆盖问题

用python写了个棋盘覆盖问题，效果图如下

#coding=utf-8

from PyQt5.QtWidgets import QWidget, QApplication
from PyQt5.QtGui import QPainter, QColor, QBrush
from PyQt5.QtCore import Qt
import sys


class ChessBoard(QWidget):
    def __init__(self):
        super(QWidget, self).__init__()

        self.board = []
        for i in range(16):
            self.board.append([])
            for j in range(16):
                self.board[i].append(0)
        self.tile = 1
        self._ChessBoard(0, 0, 3, 4, 16)

        self.initUI()


    def initUI(self):
        self.setGeometry(400, 200, 320, 320)

        self.show()

    # 绘制图形
    def paintEvent(self, QPaintEvent):
        painter = QPainter()
        painter.begin(self)
        brush = QBrush(Qt.SolidPattern)
        painter.setBrush(brush)
        for i in range(16):
            for j in range(16):
                painter.setBrush(QColor((self.board[i][j] * 11) % 255, (self.board[i][j] * 13) % 255, (self.board[i][j] * 17) % 255))
                painter.drawRect(i * 20, j * 20, i * 20 + 20, j * 20 + 20)
        painter.end()


    def _ChessBoard(self, tr, tc, dr, dc, size):
        if size == 1:
            return

        self.tile = self.tile + 1
        t = self.tile
        s = size / 2

        # 左上角
        if dr < tr + s and dc < tc + s:
            self._ChessBoard(tr, tc, dr, dc, s)
        else:
            self.board[tr + s - 1][tc + s - 1] = t
            self._ChessBoard(tr, tc, tr + s - 1, tc + s - 1, s)
        # 右上角
        if dr < tr + s and dc >= tc + s:
            self._ChessBoard(tr, tc + s, dr, dc, s)
        else:
            self.board[tr + s - 1][tc + s] = t
            self._ChessBoard(tr, tc + s, tr + s - 1, tc + s, s)
        # 左下角
        if dr >= tr + s and dc < tc + s:
            self._ChessBoard(tr + s, tc, dr, dc, s)
        else:
            self.board[tr + s][tc + s - 1] = t
            self._ChessBoard(tr + s, tc, tr + s, tc + s - 1, s)
        # 右下角
        if dr >= tr + s and dc >= tc + s:
            self._ChessBoard(tr + s, tc + s, dr, dc, s)
        else:
            self.board[tr + s][tc + s] = t
            self._ChessBoard(tr + s, tc + s, tr + s, tc + s, s)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    cb = ChessBoard()
    sys.exit(app.exec_())

参考文献：
https://blog.youkuaiyun.com/qq_30268545/article/details/80600064
https://my.oschina.net/silenceyawen/blog/650468?p={{totalpage}}