from cs1graphics import *

numLevels = 8                             # number of levels
unitSize = 12                             # the height of one level
screenSize = unitSize * (numLevels + 1)
paper = Canvas(screenSize, screenSize)

# create levels from top to bottom
for level in range(numLevels):
    width = (level + 1) * unitSize        # width varies by level
    block = Rectangle(width, unitSize)    # height is always unitSize
    centerX = screenSize - (2+level)*unitSize/ 2.0            # NEW FORMULA
    centerY = (level + 1) * unitSize
    block.move(centerX, centerY)
    block.setFillColor('gray')
    paper.add(block)