一些递归的小例子——Python

        尝试写了一些递归的例子：如PascalTriangle、谢尔平斯基三角形，

PascalTriangle

def TriangleList(num):
    if num==1:
        return [1]
    elif num==2:
        return [1,1]
    else:
        List=[1,1]
        for i in range(1,num-1):
            nextnum=TriangleList(num-1)[i-1]+TriangleList(num-1)[i]
            List.insert(i,nextnum)
        return List
def PascalTriangle(num):
    for i in range(1,num+1):
        str1=' '.join(str(i) for i in TriangleList(i))
        print(str1.center(50))

代码测试结果

 谢尔平斯基三角形

from turtle import *
def drawTriangle(points,t):
    t.up()
    t.goto(points[0])
    t.down()
    t.goto(points[1])
    t.goto(points[2])
    t.goto(points[0])
def getMid(p1,p2):
    return ((p1[0]+p2[0])/2,(p1[1]+p2[1])/2)
def sierpinski(points,degree,t):
    drawTriangle(points,t)
    if degree !=0:
        sierpinski([points[0],getMid(points[0],points[1]),getMid(points[0],points[2])],degree-1,t)
        sierpinski([points[1],getMid(points[1],points[0]),getMid(points[1],points[2])],degree-1,t)
        sierpinski([points[2],getMid(points[2],points[1]),getMid(points[0],points[2])],degree-1,t)
t=Turtle()
myWin=t.getscreen()
mypoints=[(-500,-250),(0,500),(500,-250)]
sierpinski(mypoints,4,t)
myWin.exitionclick()

测试例子