add problem description automatically from url link

[billryan]

It is a new feature about writing style of problem description. Add problem description is a tedious work.
As a programmer, we should avoid writing monotonous, repetitive tasks. Here it comes! parse_source.py

The new writing style of problem can be found in Gray Code.

Usage

python scripts/parse_source.py problem_url

You can redirect the standard output to your clipboard or pbcopy or some file in your disk.

Example

python scripts/parse_source.py http://www.lintcode.com/en/problem/word-ladder/

You will get the following text from the standard output.

Given two words (_start_ and _end_), and a dictionary, find the length of
shortest transformation sequence from _start_ to _end_, such that:

  1. Only one letter can be changed at a time
  2. Each intermediate word must exist in the dictionary

#### Example

Given:  
_start_ = `"hit"`  
_end_ = `"cog"`  
_dict_ = `["hot","dot","dog","lot","log"]`  

As one shortest transformation is `"hit" -> "hot" -> "dot" -> "dog" -> "cog"`,  
return its length `5`.

#### Note

  * Return 0 if there is no such transformation sequence.
  * All words have the same length.
  * All words contain only lowercase alphabetic characters.

Paste or redirect to your markdown file, have fun with this new feature. 👍

[billryan]

从给定的 lintcode url 生成问题的 markdown 源文件已经完成，leetcode 部分的差不太多，不过因为目前主要是从 lintcode 家拷贝题目描述的，所以暂时不去折腾，有兴趣的可以参考 Lintcode 类改写给我发 PR.
主要依赖两个库，pyquery 主要用于 html 查询，速度非常快，用于查找如 tag, title, 题目难度等十分有效。html2text 则用于从 pyquery 输出的 html 解析生成 markdown.

后期规划：

1. 重构之前的书写风格，尤其是题目描述部分。
2. 加入 tags 方便归类，这个使用 Gitbook 的 glossary 功能完成，tags 也由程序自动生成。
3. 加入难度标识，这个得解析 leetcode 上的，lintcode 上的太不准了。功能已经完成，未实施。

[billryan]

Enhancement for html2text:

• <pre><code></code></pre>
• <sup></sup>