使用递归绘制金字塔

Question

我想使用cs1graphics递归地创建一个金字塔类。该类允许用户指定金字塔的层数和总宽度

cs1graphics模块：https://github.com/otfried/cs101/blob/master/modules/cs1graphics.py

我可以使用for循环来实现这一点，但我不知道如何使用递归来实现同样的事情

以下是我正在使用的代码：

from cs1graphics import *

numLevels = 8
unitSize = 12
screenSize = unitSize * (numLevels + 1)
paper = Canvas(screenSize, screenSize)

centerX = screenSize / 2.0

for level in range(numLevels):
   centerY = (level + 1) * unitSize
   leftmostX = centerX - unitSize * level / 2.0
   for blockCount in range(level + 1):
       block = Square(unitSize)
       block.move(leftmostX + unitSize * blockCount, centerY)
       block.setFillColor('gray')
       paper.add(block)

这是我的尝试：

class Pyramid(Drawable):
    def __init__(self, numLevels, unitSize):
        screenSize = self.unitSize * (self.numLevels + 1)
        paper = Canvas(screenSize, screenSize)
        centerX = screenSize / 2.0

我不知道如何完成剩下的课程

Answer 1

像这样的方法应该会奏效： 在init中，将所有信息存储为类变量，并调用更新当前级别的递归函数。当级别达到一个基本情况时（例如，如果你正在倒计时，则达到0；如果你正在倒计时，则达到numLevels），则停止递归

from cs1graphics import *
class Pyramid(Drawable):
    def __init__(self, numLevels, unitSize):
      self.numLevels = numLevels
      self.currentlevel = 0
      self.unitSize = unitSize
      self.screenSize = unitSize * (numLevels + 1)
      self.paper = Canvas(screenSize, screenSize)
      self.centerX = screenSize / 2.0
      self.draw_pyramid()

    def draw_pyramid(self):
       centerY = (self.currentlevel + 1) * self.unitSize
       leftmostX = self.centerX - self.unitSize * self.currentlevel / 2.0
       for blockCount in range(self.currentlevel + 1):
         block = Square(self.unitSize)
         block.move(leftmostX + self.unitSize * blockCount, centerY)
         block.setFillColor('gray')
         self.paper.add(block)
       self.currentlevel += 1
       if self.currentlevel == self.numLevels:
         return
       self.draw_pyramid()