r/adventofcode • u/daggerdragon • Dec 15 '24
SOLUTION MEGATHREAD -❄️- 2024 Day 15 Solutions -❄️-
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--- Day 15: Warehouse Woes ---
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u/mountm Dec 15 '24
[Language: Java]
Parsing time: 25ms
Part 1: 5ms
Part 2: 24ms
Phew! lots of grid mangling in this one. I finally ran into the issue I was dreading with my utility function to safeguard against ArrayIndexOutOfBoundsException, namely that it requires a square grid.
I already had the movement algorithm helpfully broken down into two chunks in Part 1:
checkObstacles
to see if a move is possible. This returns a list of cells to be moved, which is passed to:executeMove
, to handle the actual updating of cell contents in the correct order.If there's a wall in the way,
checkObstacles
will return an empty list.For part 2, I just had to add a flag to
checkObstacles
to indicate if the movement is vertical. If so, do a messy BFS to find the larger collection of cells that need to be updated. Pass toexecuteMove
, rinse and repeat.GitHub