Day 5: If You Give a Seed a Fertilizer
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FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
🔒This post will be unlocked when there is a decent amount of submissions on the leaderboard to avoid cheating for top spots
🔓 Unlocked after 27 mins (current record for time, hard one today)
Rust
Ooof. Part 1 was easy enough, but for part two I initially went with the naive solution of trying every single seed which took more than a minute (I never really measured). Although that got me the right answer, to me that was just unacceptable.
I proceeded to try and combine all mappings into one but gave up after spending way too much time on it.
Then I had the idea that the lowest number in the end must lie at the beginning of a range somewhere. Either the start of a seed range in the beginning or the start of a range in one of the mappings. Any in-between numbers must end up with a higher result. So I considered the start points of all ranges, went through the mappings in reverse to find out if that point is actually within a seed range, and only tested those starting points.
Finally I had only 183 points to test which ran much faster (0.9ms).
Then I had the idea that the lowest number in the end must lie at the beginning of a range somewhere. Either the start of a seed range in the beginning or the start of a range in one of the mappings.
This really helped me out. I was stuck on either trying every single seed, or working backwards and trying every single location from 0 to infinity, and couldn’t wrap my head around how to filter down the list to be manageable. Your comment made it all make sense.
In the end, was able to work backwards with the 172 lowest locations in each range to get potential seeds, and from there was able to get a short list of 89 valid seeds (including the original seed values) to then figure out which one has the shortest location.
Thanks!
I’m a little confused about this one. The mappings are total, that is any number that is not defined explicitly gets mapped to itself. So it’s easy to create an example where the lowest number does not get mentioned within a range:
seeds: 0 3 seed-to-soil map: 10 0 2 soil-to-fertilizer map: 100 200 5 fertilizer-to-water map: 100 200 5 water-to-light map: 100 200 5 light-to-temperature map: 100 200 5 temperature-to-humidity map: 100 200 5 humidity-to-location map: 100 200 5
Here, we have seeds 0, 1 and 2. seed 0 gets mapped to location 10, seed 1 gets mapped to location 11 and seed 2 gets mapped to location 2. That means location 2 would be the answer, but it’s not a start of any range. I guess this just doesn’t happen in any of the inputs?
EDIT: actually it’s double weird. If you implemented a backwards search, that is you create reverse mappings and then try out all locations (which is what I and many others did), the result of the above example is location 0, whereas if you create a forwards brute force of all seeds, the result is 2. For the reverse approach to work in all cases, the mappings would have to be bijective.
Indeed, my solution fails on this input (returns 10, which is the location to seed 0), but it can be easily solved by also adding the ends of each range as well.
Maybe the input was quite forgiving. Thinking about it more, reversing the mapping can get quite involved, because it is neither surjective nor injective, so the inverse can actually have any number of results.
In your example there is no input that maps to 0, but there are two inputs that map to 11 (1 and 11). If the seed-to-soil map also included
10 20 2
, 21 would also map to 11.
[JavaScript] Well that was by far the hardest out of all of the days, part 1 was relatively fine but part 2 took me awhile of trying different things
Ended up solving it by working backwards by trying different location values and seeing if that can become a valid seed. Takes around 3 secs to compute the answer.
Part 1 Code Block
// Part 1 // ====== function part1(input) { const split = input.split("\r\n\r\n"); let pastValues = split[0].match(/\d+/g).map((x) => parseInt(x)); let currentValues = []; for (const section of split.slice(1)) { for (const line of section.split("\r\n")) { const values = line.match(/\d+/g)?.map((x) => parseInt(x)); if (!values) { continue; } const sourceStart = values[1]; const destinationStart = values[0]; const length = values[2]; for (let i = 0; i < pastValues.length; i++) { if ( pastValues[i] >= sourceStart && pastValues[i] < sourceStart + length ) { currentValues.push(destinationStart + pastValues[i] - sourceStart); pastValues.splice(i, 1); i--; } } } for (let i = 0; i < pastValues.length; i++) { currentValues.push(pastValues[i]); } pastValues = [...currentValues]; currentValues = []; } return Math.min(...pastValues); }
Part 2 Code Block
// Part 2 // ====== function part2(input) { const split = input.split("\r\n\r\n"); let seeds = split[0].match(/\d+/g).map((x) => parseInt(x)); seeds = seeds .filter((x, i) => i % 2 == 0) .map((x, i) => [x, seeds[i * 2 + 1]]); const maps = split .slice(1) .map((x) => { const lines = x.split("\r\n"); return lines .map((x) => x.match(/\d+/g)?.map((x) => parseInt(x))) .filter((x) => x); }) .reverse(); for (let i = 0; true; i++) { let curValue = i; for (const map of maps) { for (const line of map) { const sourceStart = line[1]; const destinationStart = line[0]; const length = line[2]; if ( curValue >= destinationStart && curValue < destinationStart + length ) { curValue = sourceStart + curValue - destinationStart; break; } } } for (const [seedRangeStart, seedRangeLength] of seeds) { if ( curValue >= seedRangeStart && curValue < seedRangeStart + seedRangeLength ) { return i; } } } }
Torn between doing the problem backwards and implementing a more general case – glad to know both approaches work out in the end!
Ended up solving it by working backwards by trying different location values and seeing if that can become a valid seed.
Huh, that’s clever.
Turns out I got really lucky and my location value is much lower than most peoples which is why it can be solved relatively quickly
Finally. :cries:
Part 1 was fine, I was figuring I might be able to practice classes.
Part 2 told me that nope, memory management required for you. In the end instead of calculating seeds, I resolved the whole thing down to a single mapping of seeds to locations. Then I could just sort by location ranges and try to see if they were a seed. Code is full of old parts from failed solutions but I’ve had enough of day 5, so I no longer care to clean it up.
Odin
When I read the problem description I expected the input to also be 2 digit numbers. When I looked at it I just had to say “huh.”
Second part I think you definitely have to do in reverse (edit: if you are doing a linear search for the answer), as that allows you to nope out as soon as you find a match, whereas with doing it forward you have to keep checking just in case.
package day5 import "core:fmt" import "core:strings" import "core:slice" import "core:strconv" Range :: struct { dest: int, src: int, range: int, } Mapper :: struct { ranges: []Range, } parse_range :: proc(s: string) -> (ret: Range) { rest := s parseLen := -1 destOk: bool ret.dest, destOk = strconv.parse_int(rest, 10, &parseLen) rest = strings.trim_left_space(rest[parseLen:]) srcOk: bool ret.src, srcOk = strconv.parse_int(rest, 10, &parseLen) rest = strings.trim_left_space(rest[parseLen:]) rangeOk: bool ret.range, rangeOk = strconv.parse_int(rest, 10, &parseLen) return } parse_mapper :: proc(ss: []string) -> (ret: Mapper) { ret.ranges = make([]Range, len(ss)-1) for s, i in ss[1:] { ret.ranges[i] = parse_range(s) } return } parse_mappers :: proc(ss: []string) -> []Mapper { mapsStr := make([dynamic][]string) defer delete(mapsStr) restOfLines := ss isLineEmpty :: proc(s: string)->bool {return len(s)==0} for i, found := slice.linear_search_proc(restOfLines, isLineEmpty); found; i, found = slice.linear_search_proc(restOfLines, isLineEmpty) { append(&mapsStr, restOfLines[:i]) restOfLines = restOfLines[i+1:] } append(&mapsStr, restOfLines[:]) return slice.mapper(mapsStr[1:], parse_mapper) } apply_mapper :: proc(mapper: Mapper, num: int) -> int { for r in mapper.ranges { if num >= r.src && num - r.src < r.range do return num - r.src + r.dest } return num } p1 :: proc(input: []string) { maps := parse_mappers(input) defer { for m in maps do delete(m.ranges) delete(maps) } restSeeds := input[0][len("seeds: "):] min := 0x7fffffff for len(restSeeds) > 0 { seedLen := -1 seed, seedOk := strconv.parse_int(restSeeds, 10, &seedLen) restSeeds = strings.trim_left_space(restSeeds[seedLen:]) fmt.print(seed) for m in maps { seed = apply_mapper(m, seed) fmt.print(" ->", seed) } fmt.println() if seed < min do min = seed } fmt.println(min) } apply_mapper_reverse :: proc(mapper: Mapper, num: int) -> int { for r in mapper.ranges { if num >= r.dest && num - r.dest < r.range do return num - r.dest + r.src } return num } p2 :: proc(input: []string) { SeedRange :: struct { start: int, len: int, } seeds := make([dynamic]SeedRange) restSeeds := input[0][len("seeds: "):] for len(restSeeds) > 0 { seedLen := -1 seedS, seedSOk := strconv.parse_int(restSeeds, 10, &seedLen) restSeeds = strings.trim_left_space(restSeeds[seedLen:]) seedL, seedLOk := strconv.parse_int(restSeeds, 10, &seedLen) restSeeds = strings.trim_left_space(restSeeds[seedLen:]) append(&seeds, SeedRange{seedS, seedL}) } maps := parse_mappers(input) defer { for m in maps do delete(m.ranges) delete(maps) } for i := 0; true; i += 1 { rseed := i #reverse for m in maps { rseed = apply_mapper_reverse(m, rseed) } found := false for sr in seeds { if rseed >= sr.start && rseed < sr.start + sr.len { found = true break } } if found { fmt.println(i) break } } }
Haskell
Not hugely proud of this one; part one would have been easier if I’d spend more time reading the question and not started on an overly-general solution, and I lost a lot of time on part two to a missing
a +
. More haste, less speed, eh?import Data.List import Data.List.Split readInput :: String -> ([Int], [(String, [(Int, Int, Int)])]) readInput s = let (seedsChunk : mapChunks) = splitOn [""] $ lines s seeds = map read $ tail $ words $ head seedsChunk maps = map readMapChunk mapChunks in (seeds, maps) where readMapChunk (title : rows) = let name = head $ words title entries = map ((\[a, b, c] -> (a, b, c)) . map read . words) rows in (name, entries) part1 (seeds, maps) = let f = foldl1' (flip (.)) $ map (ref . snd) maps in minimum $ map f seeds where ref [] x = x ref ((a, b, c) : rest) x = let i = x - b in if i >= 0 && i < c then a + i else ref rest x mapRange :: [(Int, Int, Int)] -> (Int, Int) -> [(Int, Int)] mapRange entries (start, end) = go start $ sortOn (\(_, b, _) -> b) entries where go i [] = [(i, end)] go i es@((a, b, c) : rest) | i > end = [] | b > end = go i [] | b + c <= i = go i rest | i < b = (i, b - 1) : go b es | otherwise = let d = min (b + c - 1) end in (a + i - b, a + d - b) : go (d + 1) rest part2 (seeds, maps) = let seedRanges = map (\[a, b] -> (a, a + b - 1)) $ chunksOf 2 seeds in minimum $ map fst $ foldl' (flip mapRanges) seedRanges $ map snd maps where mapRanges m = concatMap (mapRange m) main = do input <- readInput <$> readFile "input05" print $ part1 input print $ part2 input
Nim
Woof. Part 1 was simple enough. I thought I could adapt my solution to part 2 pretty easily, just add all the values in the ranges to the starting set. Worked fine for the example, but the ranges for the actual input are too large. Ended up taking 16gb of RAM and crunching forever.
I finally abandoned my quick and dirty approach when rewriting part 2, and made some proper types and functions. Treated each range as an object, and used set operations on them. 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.
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.
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.
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 twoseq
s 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!
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.Thank you, should be fixed now.
Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn’t work well for people on different instances. Try fixing it like this: !nim@programming.dev
Scala3
kind of convoluted, but purely functional
import scala.collection.immutable.NumericRange.Exclusive import math.max import math.min extension [A] (l: List[A]) def chunk(pred: A => Boolean): List[List[A]] = def go(l: List[A], partial_acc: List[A], acc: List[List[A]]): List[List[A]] = l match case (h :: t) if pred(h) => go(t, List(), partial_acc.reverse :: acc) case (h :: t) => go(t, h :: partial_acc, acc) case _ => partial_acc.reverse :: acc go(l, List(), List()).reverse type R = Exclusive[Long] def intersectTranslate(r: R, c: R, t: Long): R = (t + max(r.start, c.start) - c.start) until (t + min(r.end, c.end) - c.start) case class MappingEntry(from: R, to: Long) case class Mapping(entries: List[MappingEntry], produces: String): def resolveRange(in: R): List[R] = entries.map(e => intersectTranslate(in, e.from, e.to)).filter(!_.isEmpty) def completeEntries(a: List[MappingEntry]): List[MappingEntry] = a ++ ((0L until 0L) +: a.map(_.from).sorted :+ (Long.MaxValue until Long.MaxValue)).sliding(2).flatMap{ case List(a, b) => Some(MappingEntry(a.end until b.start, a.end)); case _ => None}.toList def parse(a: List[String], init: List[Long] => List[R]): (List[R], Map[String, Mapping]) = def parseEntry(s: String): MappingEntry = s match case s"$end $start $range" => MappingEntry(start.toLong until start.toLong + range.toLong, end.toLong) a.chunk(_ == "") match case List(s"seeds: $seeds") :: maps => init(seeds.split(raw"\s+").map(_.toLong).toList) -> (maps.flatMap{ case s"$from-to-$to map:" :: entries => Some(from -> Mapping(completeEntries(entries.map(parseEntry)), to)); case _ => None }).toMap case _ => (List(), Map()).ensuring(false) def singletons(a: List[Long]): List[R] = a.map(s => s until s + 1) def paired(a: List[Long]): List[R] = a.grouped(2).flatMap{ case List(x, y) => Some(x until x+y); case _ => None }.toList def chase(d: (List[R], Map[String, Mapping]), initial: String, target: String) = val (init, m) = d def go(a: List[R], s: String): List[R] = if trace(s) == target then a else val x = m(s) go(a.flatMap(x.resolveRange), x.produces) go(trace(init), initial) def task1(a: List[String]): Long = chase(parse(a, singletons), "seed", "location").min.start def task2(a: List[String]): Long = chase(parse(a, paired), "seed", "location").min.start
This was interesting! So iterating through the solution space would be infeasible here and it seems we need to look for boundaries between regions and follow them to find places where a solution could occur.
Python: https://pastebin.com/8Ckx36fu
- Make a list of places where location mappings are discontinuous (0, the end of each mapping, and the number before)
- Repeat this for discontinuities in each intermediate layer
- Trace each such location to its seed, and filter by seed ranges
- Run the very minimal set of interesting seed numbers (around 2000 seeds) through the existing part1 algorithm
Like many others, I really didn’t enjoy this one. I particularly struggled with part 02, which ended up with me just brute forcing it and checking each seed. On my system it took over 15 minutes to run, which is truly awful. I’m open to pointers on how I could better have solved part two.
Solution in Rust 🦀
Code
use std::{ env, fs, io::{self, BufReader, Read}, }; fn main() -> io::Result<()> { let args: Vec = env::args().collect(); let filename = &args[1]; let file1 = fs::File::open(filename)?; let file2 = fs::File::open(filename)?; let mut reader1 = BufReader::new(file1); let mut reader2 = BufReader::new(file2); println!("Part one: {}", process_part_one(&mut reader1)); println!("Part two: {}", process_part_two(&mut reader2)); Ok(()) } #[derive(Debug)] struct Map { lines: Vec, } impl Map { fn map_to_lines(&self, key: u32) -> u32 { for line in &self.lines { if line.in_range(key) { return line.map(key); } } key } } #[derive(Debug)] struct MapLine { dest_range: u32, source_range: u32, range_length: u32, } impl MapLine { fn map(&self, key: u32) -> u32 { let diff = key - self.source_range; if self.dest_range as i64 + diff as i64 > 0 { return (self.dest_range as i64 + diff as i64) as u32; } key } fn in_range(&self, key: u32) -> bool { self.source_range <= key && (key as i64) < self.source_range as i64 + self.range_length as i64 } } fn parse_input(reader: &mut BufReader) -> (Vec, Vec<map>) { let mut almanac = String::new(); reader .read_to_string(&mut almanac) .expect("read successful"); let parts: Vec<&str> = almanac.split("\n\n").collect(); let (seeds, others) = parts.split_first().expect("at least one part"); let seeds: Vec<_> = seeds .split(": ") .last() .expect("at least one") .split_whitespace() .map(|s| s.to_string()) .collect(); let maps: Vec<_> = others .iter() .map(|item| { let lines_iter = item .split(':') .last() .expect("exists") .trim() .split('\n') .map(|nums| { let nums_split = nums.split_whitespace().collect::>(); MapLine { dest_range: nums_split[0].parse().expect("is digit"), source_range: nums_split[1].parse().expect("is digit"), range_length: nums_split[2].parse().expect("is digit"), } }); Map { lines: lines_iter.collect(), } }) .collect(); (seeds, maps) } fn process_part_one(reader: &mut BufReader) -> u32 { let (seeds, maps) = parse_input(reader); let mut res = u32::MAX; for seed in &seeds { let mut val = seed.parse::().expect("is digits"); for map in &maps { val = map.map_to_lines(val); } res = u32::min(res, val); } res } fn process_part_two(reader: &mut BufReader) -> u32 { let (seeds, maps) = parse_input(reader); let seed_chunks: Vec<_> = seeds.chunks(2).collect(); let mut res = u32::MAX; for chunk in seed_chunks { let range_start: u32 = chunk[0].parse().expect("is digits"); let range_length: u32 = chunk[1].parse().expect("is digits"); let range_end: u32 = range_start + range_length; for seed in range_start..range_end { let mut val = seed; for map in &maps { val = map.map_to_lines(val); } res = u32::min(res, val); } } res } #[cfg(test)] mod tests { use super::*; const INPUT: &str = "seeds: 79 14 55 13 seed-to-soil map: 50 98 2 52 50 48 soil-to-fertilizer map: 0 15 37 37 52 2 39 0 15 fertilizer-to-water map: 49 53 8 0 11 42 42 0 7 57 7 4 water-to-light map: 88 18 7 18 25 70 light-to-temperature map: 45 77 23 81 45 19 68 64 13 temperature-to-humidity map: 0 69 1 1 0 69 humidity-to-location map: 60 56 37 56 93 4"; #[test] fn test_process_part_one() { let input_bytes = INPUT.as_bytes(); assert_eq!(35, process_part_one(&mut BufReader::new(input_bytes))); } #[test] fn test_process_part_two() { let input_bytes = INPUT.as_bytes(); assert_eq!(46, process_part_two(&mut BufReader::new(input_bytes))); } }
:::</map>
I got far enough to realize that you probably needed to work backwards and given a location, determine the accompanying seed, and then check if that seed is one of the ones listed in the range. Still though, starting at 0 for location and working up was taking forever to find the first valid seed
Someone in this thread pointed out that if you picked the first value of each range in the map, working backwards from those points will get you a short list of seeds which map to low values. You then check if those seeds are valid, and also check the location of the first seeds in the range (the rest of the seeds in the range don’t matter because those are covered by the first check). This ends up with about 200 locations which you can sort, to get the lowest value.
I tried brute forcing it but couldn’t get the process to finish. Iterating through hundreds of millions of seeds is no bueno.
After reading your comment though I got the idea to map whole seed ranges instead of individual seeds. That finished in no time of course.
deleted by creator
[C]
My first approach to part 2 was to take the list of ranges, map it to a new list of (possibly split up) ranges, etc, but I realized that would take more memory and bookkeeping than I’d like. Scrapped it and rewrote it with recursion. Much cleaner and the benchmarks are still looking good! (But for how much longer?)
$ bmake bench day01 0:00.00 1380 Kb 0+78 faults day02 0:00.00 1660 Kb 0+82 faults day03 0:00.00 1540 Kb 0+107 faults day04 0:00.00 1536 Kb 0+80 faults day05 0:00.00 1668 Kb 0+83 faults
https://github.com/sjmulder/aoc/blob/master/2023/c/day05.c
Edit: I see some people went for looping from 0 to try possible answers. Clever and short but I wanted to go for a more efficient approach.
Ah, nice! Dealing with each range individually makes things much simpler.
Well, I can’t say much about this one. The code is ugly, horribly inefficient, and part two takes a solid half hour to run. It got the right answer though, so that’s something I suppose. I think something like
nom
to parse the input would be much cleaner, and there’s got to be a better way of going about part two than just brute forcing through every possible seed, but hey, it works so that’s good enough for now.https://github.com/capitalpb/advent_of_code_2023/blob/main/src/solvers/day05.rs
#[derive(Clone, Debug)] struct AlmanacMapEntry { destination_range: RangeInclusive, source_range: RangeInclusive, } #[derive(Clone, Debug)] struct AlmanacMap { entries: Vec, } impl AlmanacMap { fn from(input: &str) -> AlmanacMap { let entries = input .lines() .skip(1) .map(|line| { let numbers = line .split(' ') .filter_map(|number| number.parse::().ok()) .collect::>(); AlmanacMapEntry { destination_range: numbers[0]..=(numbers[0] + numbers[2]), source_range: numbers[1]..=(numbers[1] + numbers[2]), } }) .collect(); AlmanacMap { entries } } fn convert(&self, source: &u64) -> u64 { let entry = self .entries .iter() .find(|entry| entry.source_range.contains(&source)); if let Some(entry) = entry { entry.destination_range.start() + (source - entry.source_range.start()) } else { source.clone() } } } #[derive(Debug)] struct Almanac { seeds: Vec, seed_to_soil: AlmanacMap, soil_to_fertilizer: AlmanacMap, fertilizer_to_water: AlmanacMap, water_to_light: AlmanacMap, light_to_temperature: AlmanacMap, temperature_to_humidity: AlmanacMap, humidity_to_location: AlmanacMap, } impl Almanac { fn star_one_from(input: &str) -> Almanac { let mut input_sections = input .split("\n\n") .map(|section| section.split_once(':').unwrap().1); let seeds = input_sections .next() .unwrap() .split_whitespace() .filter_map(|seed| seed.parse::().ok()) .collect(); let almanac_maps = input_sections.map(AlmanacMap::from).collect::>(); Almanac { seeds, seed_to_soil: almanac_maps[0].clone(), soil_to_fertilizer: almanac_maps[1].clone(), fertilizer_to_water: almanac_maps[2].clone(), water_to_light: almanac_maps[3].clone(), light_to_temperature: almanac_maps[4].clone(), temperature_to_humidity: almanac_maps[5].clone(), humidity_to_location: almanac_maps[6].clone(), } } fn star_two_from(input: &str) -> Almanac { let mut input_sections = input .split("\n\n") .map(|section| section.split_once(':').unwrap().1); let seeds = input_sections .next() .unwrap() .split_whitespace() .filter_map(|seed| seed.parse::().ok()) .collect::>() .chunks(2) .map(|chunk| (chunk[0]..(chunk[0] + chunk[1])).collect::>()) .flatten() .collect::>(); let almanac_maps = input_sections.map(AlmanacMap::from).collect::>(); Almanac { seeds, seed_to_soil: almanac_maps[0].clone(), soil_to_fertilizer: almanac_maps[1].clone(), fertilizer_to_water: almanac_maps[2].clone(), water_to_light: almanac_maps[3].clone(), light_to_temperature: almanac_maps[4].clone(), temperature_to_humidity: almanac_maps[5].clone(), humidity_to_location: almanac_maps[6].clone(), } } } pub struct Day05; impl Solver for Day05 { fn star_one(&self, input: &str) -> String { let almanac = Almanac::star_one_from(input); almanac .seeds .iter() .map(|seed| almanac.seed_to_soil.convert(seed)) .map(|soil| almanac.soil_to_fertilizer.convert(&soil)) .map(|fertilizer| almanac.fertilizer_to_water.convert(&fertilizer)) .map(|water| almanac.water_to_light.convert(&water)) .map(|light| almanac.light_to_temperature.convert(&light)) .map(|temperature| almanac.temperature_to_humidity.convert(&temperature)) .map(|humidity| almanac.humidity_to_location.convert(&humidity)) .min() .unwrap() .to_string() } fn star_two(&self, input: &str) -> String { let almanac = Almanac::star_two_from(input); almanac .seeds .iter() .map(|seed| almanac.seed_to_soil.convert(seed)) .map(|soil| almanac.soil_to_fertilizer.convert(&soil)) .map(|fertilizer| almanac.fertilizer_to_water.convert(&fertilizer)) .map(|water| almanac.water_to_light.convert(&water)) .map(|light| almanac.light_to_temperature.convert(&light)) .map(|temperature| almanac.temperature_to_humidity.convert(&temperature)) .map(|humidity| almanac.humidity_to_location.convert(&humidity)) .min() .unwrap() .to_string() } }
Nim
Part 1 was really easy.
Part 2, I struggled to solve efficiently, so I just ran naive bruteforce for 5 minutes until I got the answer.
Later, I’ve rewritten my solution for Part 2. The idea is to handle ranges as ranges, check seed ranges against map ranges, transform overlaps, but keep not-overlapping parts.Total runtime after rewrite: ~ 0.4 ms.
Today’s puzzle was nice - 8.5/10.Code: day_05/solution.nim
Python
Questions and feedback welcome!
import portion as P from .solver import Solver _maps = [ 'seed-to-soil', 'soil-to-fertilizer', 'fertilizer-to-water', 'water-to-light', 'light-to-temperature', 'temperature-to-humidity', 'humidity-to-location', ] def group_lines_in_maps(lines): group = [] for line in lines: if not line: yield group group = [] continue group.append(line) yield group class Day05(Solver): def __init__(self): super().__init__(5) self.seeds = [] self.mappings = {} def presolve(self, input: str): lines = input.rstrip().split('\n') self.seeds = list(map(int, lines[0].split(' ')[1:])) self.mappings = {} for mapping in group_lines_in_maps(lines[2:]): mapping_name = mapping[0].split(' ')[0] mapping_ranges = map(lambda rng: tuple(map(int, rng.split(' '))), mapping[1:]) self.mappings[mapping_name] = list(mapping_ranges) def solve_first_star(self): locations = [] for seed in self.seeds: location = seed for mapping in map(self.mappings.get, _maps): assert mapping for dest, source, length in mapping: if 0 <= location - source < length: location = dest + (location - source) break locations.append(location) return min(locations) def solve_second_star(self): current_set = P.empty() for i in range(0, len(self.seeds), 2): current_set = current_set | P.closedopen(self.seeds[i], self.seeds[i] + self.seeds[i + 1]) for mapping in map(self.mappings.get, _maps): assert mapping unmapped = current_set next_set = P.empty() for dest, source, length in mapping: delta = dest - source source_range = P.closedopen(source, source + length) mappable = unmapped & source_range mapped_to_destination = mappable.apply( lambda x: (x.left, x.lower + delta, x.upper + delta, x.right)) # pylint: disable=cell-var-from-loop next_set = next_set | mapped_to_destination unmapped = unmapped - source_range current_set = next_set | unmapped return next(P.iterate(current_set, step=1))
Honestly this one was quite easy for me. Not so much for my computer though…
https://git.sr.ht/~aidenisik/aoc23/tree/master/item/day5
C solutions. Disclaimer, part 2 has not finished running. But it’s mostly the same code as part 1 and it works on the small sample data so it’ll be fine.
Disclaimer, part 2 has not finished running. But it’s mostly the same code as part 1 and it works on the small sample data so it’ll be fine.
RIP?
Still running :)
I don’t have the most powerful hardware unfortunately