Please note that this forum is for things like official forum challenges, suggestions for those kinds of challenges, and (subject to approval) advertisements for challenges external to the forum. It is not a place for questions which the asker considers challenging, or for homework to be posed as a challenge to our forum members. Mods and admins will move such posts to an appropriate forum or delete them if they're extremely egregious (e.g. homework).
Due to the reasons discussed here
we will be moving to python-forum.io
on October 1, 2016.
This forum will be locked down and no one will be able to post/edit/create threads, etc. here from thereafter. Please create an account at the new site to continue discussion.