[AlgoCollector] Improve weekly problems comment picking

[ledongthuc]

Source code: https://github.com/ruby-vietnam/hardcore-rule/tree/master/algorithms/collector

Background

• Algorithm collector access Algorithm weekly report page to get "Weekly problems". It always expects the latest comment on the page as the latest problems of the current week.

Problems

• Sometimes, we have to discuss or add comments on Algorithm weekly report page that makes the latest comment on the page is not the latest problems comment.

Proposal

• When checking comments of Algorithm weekly report page, we check starting pattern "Weekly problem:" as first problems posts and assume it's problem's comments.
• Algorithm collector use the latest comment that starts with "Weekly problem:" and expect it as the latest problems comment. Other comments without starting of "Weekly problem:", we skip it.
• Trim space/tab to avoid typing problems.
• Allows custom starting problem patterns from the variable environments. Default is "Weekly problem:"