Yeah! Today is day 12, and again the exercise felt relatively simple.
No new things to learn, just using a map as unidirectional graph (the text promised that each side of the pipe will report it in the input!).
For the first part I simply started at pid 0, did a depth first search and inserting all childs of the current node to a set, removing the current node and then continuing the search. I cancelled depth search when a given link pointed to a node that was already removed and continued searching in breadth then. At the end I counted the elements in the resulting set.
The second part used that way as well, but ignorig the set, only using the updated map in each iteration until it was empty. Each iteration incremented a counter by 1. I used Enum.at/2 to actually get a pid to start the search from.
