python challenge level 4

趁着今天周末，就把做过的几个level全部发上来，现在更新的是level 4

题目链接

http://www.pythonchallenge.com/pc/def/linkedlist.php

思路

从网页中的图片又是看不出什么规律，那么就只好继续查看页面源代码了，其中有这个一句注释：

<!-- urllib may help. DON'T TRY ALL NOTHINGS, since it will never 
end. 400 times is more than enough. -->

<a href="linkedlist.php?nothing=12345">

其中还有一个链接，是linkedlist.php?nothing=12345，先输入看看

http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=12345

输出结果

and the next nothing is 44827

那么继续替换nothing后面的数字

http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=44827

输出结果

and the next nothing is 45439

再按照注释中不超过400次的意思，应该是说这个nothing后面的数字要替换400次，就可以得出下一个网址

#!/usr/bin/env python3

from urllib.request import urlopen
import re

prefix = "http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing="
number = ['12345']

"""
for i in range(400):
    try:
        print(prefix + number[0])
    except:
        print("find the last")
        print (number)

    sock = urlopen(prefix + number[0])
    number = re.findall('([0-9]+)$', sock.read().decode('utf-8'), re.S)
"""

for i in range(400):
    try:
        print(prefix + number[0])
    except:
        print("find")
        print(number)
    sock = urlopen(prefix + number[0])
    number = re.findall('([0-9]+)$', sock.read().decode('utf-8'), re.S)

结果上面的跑到这个页面停止了

http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=16044

输出结果

Yes. Divide by two and keep going.

那么就把16044 / 2，继续

最后停在

http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=66831

输出是

peak.html

输入

http://www.pythonchallenge.com/pc/def/peak.html

进入level 5