Python Challenge 第4关

第4关：这一关才开始推荐使用​​urllib​​，无妨。打开源码发现注释：

urllib may help. DON’T TRY ALL NOTHINGS, since it will never end. 400 times is more than enough.

点击图片发现可以跳转，​​url=http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=12345​​​，替换​​12345​​​为页面中next nothing的值：​​44827​​，然后多替换几次，就可以发现规律，一点点消除URL的异常。为了节省时间，每次开始可以从抛异常的上一个数开始执行，只需要替换url中的nothing值即可。

第一次：​​Yes. Divide by two and keep going.​​​，把上次值除以2.
第二次：​​​There maybe misleading numbers in the text. One example is 82683. Look only for the next nothing and the next nothing is 63579​​​ 第三次：​​peak.html​​，这就是下一关的URL。

1. 获取源码

import urllib.request

def get_html_page(url):
    page = None
    resp = urllib.request.urlopen(url)
    if (resp.status == 200):
        page = resp.read().decode('utf-8')
    return page

1. 获取注释

def get_comments(page):
    rs = re.findall('<!--\s*(.*?)\s*-->', page, re.S)
    print(rs)
    if rs:
        return rs[0] # 注意这里是0
    return None

1. 主函数

def main():
    url = 'http://www.pythonchallenge.com/pc/def/equality.html'

    page = get_html_page(url)
    comments = get_comments(page)
    print(comments)
    rs = re.findall('[^A-Z][A-Z]{3}([a-z])[A-Z]{3}[^A-Z]', comments, re.S)
    print("".join(rs))

下一关URL：​​http://www.pythonchallenge.com/pc/def/peak.html​​