Have to admit, on first glance this challenge looks a bit complicated. It's well suited for languages which can do string manipulations, but it's not well suited for PostgreSQL. Earlier today I already looked at this problem together with the kid, in Python. Therefore I already knew that I have to jump multiple rows as well. To sum it up: adjust x, including overruns, jump multiple rows in y direction, count trees along the way. All in a single SQL query.
Decided to do the map search in a pl/pgSQL instead, and write a function for it.
Task 1: you get a map of "." and "#", where the "#" are trees. You get instructions to move a certain number of steps into x and y direction, and see if there is a tree. Then repeat until the end of the map. A detail problem is that the number of fields in x direction is smaller than the y direction. There are no clear instructions how to handle this, but the correct solution is to just start at the leftmost position again.
Task 2: Repeat the task from task 1, but 5 times with 5 different instructions for x and y movement. The resulting numbers are to be multiplied.Continue reading "Advent of Code 2020: "Toboggan Trajectory" - Day 3"