Oh, I see, I for some reason switched zip operation with “create pair/tuple” operation in my head. Thanks for clarification.

Wouldn’t this code fail in a case like this? Because you count different lines, not different characters in the lines, right? Or am I missing something? Thanks (Let’s ignore column symmetry for the sake of example).

##
..
..
..

(I think you will get answer 100, but the answer is 300)

But for sure after seeing this I have to learn Scala.

Kotlin

Github

Was lazy at the beginning, so I started to do actual expansion in memory, then decided to do it properly. And it paid off in the second part.

• find galaxy coordinates + hold few bit masks to find unused rows and columns → convert to indexes
• transform original galaxies coordinates considering number of previous empty lines (time for simple binary search)
• use the Manhattan distance

Kotlin

Github

Double expansion seams like a nice approach, but I didn’t think of that. Instead, I just scan the lines and “remember” if I am in a component or not by counting the number of pipe crossings.