Advent Of Code

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An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2023

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🎁 - 2023 DAY 5 SOLUTIONS -🎁 (self.advent_of_code)

submitted 11 months ago* (last edited 11 months ago) by Ategon to c/advent_of_code

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Day 5: If You Give a Seed a Fertilizer

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[–] [email protected] 1 points 11 months ago (1 children)

Treated each range as an object, and used set operations on them

That's smart. Honestly, I don't understand how it works. 😅

The difference operation tends to fragment the range that it’s used on, so I meant to write some code to defragment the ranges after each round of mappings. Forgot to do so, but the code ran quick enough this time anyway.

I've got different solution from yours, but this part is the same, lol. My code slices the ranges into 1-3 parts on each step, so I also planned to 'defragment' them. But performance is plenty without this step, ~450 microseconds for both parts on my PC.

[–] [email protected] 2 points 11 months ago (1 children)

Treated each range as an object, and used set operations on them

That’s smart. Honestly, I don’t understand how it works. 😅

"Set operations" should probably be in quotes. I just mean that I implemented the * (intersection) and - (difference) operators for my ValueRange type. The intersection operator works like it does for sets, just returning the overlap. The difference operator has to work a little differently, because ranges have to be contiguous, whereas sets don't, so it returns a sequence of ValueRange objects.

My ValueMapping type uses a ValueRange for it's source, so applying it to a range just involves using the intersection operator to determine what part of the range needs to move, and the difference operator to determine which parts are left.

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago) (1 children)

Well, then we have the same solution but coded very differently. Here's mine.

ruleApplied is one function with almost all logic. I take a range and compare it to a rule's source range (50 98 2 is a rule). Overlaps get transformed and collected into the first sequence and everything that left goes in the second. I need two seqs there, for transformed values to skip next rules in the same map.

Repeat for each rule and each map (seq[Rule]). And presto, it's working!

[–] [email protected] 2 points 11 months ago (1 children)

Yeah, roughly the same idea. I guess I could have just used HSlice for my range type, I thought maybe there was some special magic to it.

It looks like your if-else ladder misses a corner case, where one range only intersects with the first or last element of the other. Switching to <= and >= for those should take care of it though.

[–] [email protected] 1 points 11 months ago

Thank you, should be fixed now.