[Tutor] Pigs can fly?

[Danny Yoo]

Hi everyone,

I'm curious if anyone has encountered:

    http://codegolf.stackexchange.com/questions/35623/are-pigs-able-to-fly

As soon as I saw this problem, I felt strongly compelled to play with
this.  :P  Of course, I can't show any solutions, but I thought the
problem might be interesting to others here.

Even without the code minimization constraints due to "code golf" I
still think it's a worthwhile problem to work out.  It's one of those
problems that exercises multiple skills for the intermediate Python
programmer, such as input/output, parsing, knowing your data
structures, and writing good test cases.

And it makes a good case that interesting and fun problems can be
mathematical, and yet have nothing to do with basic arithmetic.
What's really being asked in the problem is a graph traversal in
disguise.