Learning something new is why I like this place. I did not know about zipper trees.

But this was a very difficult task in the wrong I my mind. Solving the problem was the easy part. Geting it to pass within the allowed time frame was an entire different story.

If you try to solve this task with erlang and you have issues with timeout, try search for

"Erlang: Read from an input stream in a efficient way"

Using module string will not work, use binaries. I also had to write my own split line method for the operations.

Good luck.