Uiua

I'm currently going through the 2025 Quests to learn Rust, committing great sins along the way.
Decided to take a shot at the third one with Uiua because it looked nice and simple, and it was. This may have been the fastest I've ever finished a complete quest :P

Run with example input

I₁   ← "10,5,1,10,3,8,5,2,2"
I₂   ← "4,51,13,64,57,51,82,57,16,88,89,48,32,49,49,2,84,65,49,43,9,13,2,3,75,72,63,48,61,14,40,77"
I₃   ← "4,51,13,64,57,51,82,57,16,88,89,48,32,49,49,2,84,65,49,43,9,13,2,3,75,72,63,48,61,14,40,77"
Prep ← ⊏⊸⍖⊜⋕⊸≠@,
P₁   ← /+◴ Prep
P₂   ← /+↙₋₂₀◴ Prep
P₃   ← +₁/↥⧆ Prep
⍚$"Part _: _" 1_2_3 [P₁I₁ P₂I₂ P₃I₃]
&pf /$$ _
     $$ _

Very simple task for Uiua.

[10 5 1 10 3 8 5 2 2]
/+◴
[4 51 13 64 57 51 82 57 16 88 89 48 32 49 49 2 84 65 49 43 9 13 2 3 75 72 63 48 61 14 40 77]
/+↙20⍆⊸◴
/↥⊜⧻⊸∘⍆

-> 29, 781, 3

Scheme/Guile

Guile doesn't seem to come with a bag implementation :(. Not a big deal, a linear scan works about as well.

(use-modules (ice-9 rdelim))
(use-modules (srfi srfi-1))

(define (parse-file file-name)
  (let* ((p (open-input-file file-name))
        (comma-split (string-split (read-line p) #\,))
        (number-list (map string->number comma-split)))
    number-list))

(let* ((crates (parse-file "notes/everybody_codes_e2025_q03_p1.txt"))
       (dedup-crates (delete-duplicates crates)))
  (format #t "P1 Answer: ~a\n\n" (apply + dedup-crates)))


(let* ((crates (parse-file "notes/everybody_codes_e2025_q03_p2.txt"))
       (dedup-crates (delete-duplicates crates))
       (sorted-crates (sort dedup-crates <)))
  (format #t "P2 Answer: ~a\n\n" (apply + (take sorted-crates 20))))


(let* ((crates (parse-file "notes/everybody_codes_e2025_q03_p3.txt"))
       (sorted-crates (sort crates <))
       (largest-set-size (let loop ((count 0) (l sorted-crates) (c #f) (max-count 0))
         (if (nil? l)
             max-count
             (let* ((new-c (car l))
                    (new-count (if (equal? new-c c) (+ count 1) 1)))
               (loop new-count (cdr l) new-c (max new-count max-count)))))))
  (format #t "P3 Answer: ~a\n\n" largest-set-size))

I thought this was going to be the knapsack problem, but no.

import Control.Monad  
import Data.List.Split  
import qualified Data.Set as Set  
import qualified Data.Multiset as MSet  

part1, part2, part3 :: [Int] -> Int  
part1 = sum . Set.fromList  
part2 = sum . Set.take 20 . Set.fromList  
part3 = maximum . MSet.toCountMap . MSet.fromList  

main =  
  forM_  
    [ ("everybody_codes_e2025_q03_p1.txt", part1),  
      ("everybody_codes_e2025_q03_p2.txt", part2),  
      ("everybody_codes_e2025_q03_p3.txt", part3)  
    ]  
    $ \(input, solve) ->  
      readFile input >>= print . solve . map read . splitOn ","  

Rust

pub fn solve_part_1(input: &str) -> String {
    let mut crates: Vec<i64> = input.split(",").map(|s| s.parse().unwrap()).collect();
    crates.sort();
    let mut monotonic_subsequence = vec![crates[0]];
    for size in crates.into_iter().skip(1) {
        if size == *monotonic_subsequence.last().unwrap() {
            continue;
        }
        monotonic_subsequence.push(size);
    }
    monotonic_subsequence.iter().sum::<i64>().to_string()
}

pub fn solve_part_2(input: &str) -> String {
    let mut crates: Vec<i64> = input.split(",").map(|s| s.parse().unwrap()).collect();
    crates.sort();
    let mut monotonic_subsequence = vec![crates[0]];
    for size in crates.into_iter().skip(1) {
        if size == *monotonic_subsequence.last().unwrap() {
            continue;
        }
        monotonic_subsequence.push(size);
        if monotonic_subsequence.len() >= 20 {
            break;
        }
    }
    monotonic_subsequence.iter().sum::<i64>().to_string()
}

pub fn solve_part_3(input: &str) -> String {
    let mut crates: Vec<i64> = input.split(",").map(|s| s.parse().unwrap()).collect();
    crates.sort();
    let mut monotonic_subsequences = vec![vec![crates[0]]];
    for size in crates.into_iter().skip(1) {
        let updateable_sequence = monotonic_subsequences
            .iter_mut()
            .find(|v| *v.last().unwrap() < size);
        match updateable_sequence {
            Some(v) => {
                v.push(size);
            }
            None => {
                monotonic_subsequences.push(vec![size]);
            }
        }
    }
    monotonic_subsequences.len().to_string()
}

Common Lisp doesn't have a built in set datatype, so you have to do uniqueness checking sort of by hand unless you want to pull in an external package.

(ql:quickload :str)

(defun read-inputs (filename)
  (let ((input-lines (uiop:read-file-lines filename)))
    (mapcar #'parse-integer (str:split "," (car input-lines)))))

(defun add-distinct (xs)
  (loop for x in (remove-duplicates (sort (copy-seq xs) #'>))
        sum x))

(defun main-1 (filename)
  (add-distinct (read-inputs filename)))

(defun main-2 (filename)
  (let* ((sizes (read-inputs filename))
         (first-20 (subseq (remove-duplicates (sort (copy-seq sizes) #'<)) 0 20)))
    (loop for x in first-20
          sum x)))

(defun count-max-copies (xs)
  (labels ((iter (xs cur-x cur-count max-count)
             (cond ((null xs)
                    max-count)
                   ((equal (car xs) cur-x)
                    (iter (cdr xs) cur-x (1+ cur-count) (max max-count (1+ cur-count))))
                   (t
                    (iter (cdr xs) (car xs) 1 max-count)))))
    (iter (cdr xs) (car xs) 1 1)))

(defun main-3 (filename)
  (count-max-copies (sort (read-inputs filename) #'<)))

Nim

Reading this day's quest I was at first a bit confused what it asks me to calculate. Took me about a minute to realize that most of descriptions are not important and actual calculations for each part are very simple:

part 1 wants sum of each unique crate size
part 2 is same but only 20 smallest
part 3 is max count, because you can always put most crates in one large set and you only need 1 extra set per duplicate crate

proc solve_part1*(input: string): Solution =
  var seen: set[int16]
  for num in input.split(','):
    let num = parseInt(num).int16
    if num in seen: continue
    else:
      seen.incl num
      result.intVal += num

proc solve_part2*(input: string): Solution =
  var set = input.split(',').mapIt(parseInt(it).uint16)
  set.sort()
  result := set.deduplicate(isSorted=true)[0..<20].sum()

proc solve_part3*(input: string): Solution =
  var cnt = input.split(',').toCountTable()
  result := cnt.largest.val

Full solution at Codeberg: solution.nim

FSharp

I'm a month late, but eh. Compared to everyone else, it looks like my approach of preserving duplicates was unnecessary. I chose to use SortedSets (redundant since I sort the inputs) and cascade to the next best fit. The sorted sets also let me grab the Max/Min values and I thought that it was more in line with the intention than having a list that happens to be sorted.

I also sorted part 1 based on what I thought was the best fit, which was the same solution for part 3.
For part 2 I duplicated part 1's logic but reversed the order to asc instead of desc, but I don't know that that made a difference and excluded it here. The only difference is the "add if count < 20".

type Crate = int  
 // sorted set because only one item can be in at a time. The SortedSet is unnecessary here since the inputs are already sorted  
type CrateSet = SortedSet<Crate>  
let inline newCrateSet crate =  
    let cs = CrateSet()  
    cs.Add(crate) |> ignore  
    cs  
type Extensions() =  
    [<Extension>]  
    static member inline SmallestCrate (crates:CrateSet) : Crate option = match crates.Min with | 0 -> None | x -> Some x  
    [<Extension>]  
    static member inline LargestCrate (crates:CrateSet) : Crate option = match crates.Max with | 0 -> None | x -> Some x  

/// take a sorted input (not verified) and prioritize insertion into the first found list.  
/// This results in cascading to the "next best fit", but this approach relies on sorted inputs.  
let packEfficiently allCrates =  
    allCrates  
    |> Seq.fold (fun sortedCrates next ->  
            // find the first crate set that can hold the next item and put it in there  
            match sortedCrates with  
            | [] -> [newCrateSet next]  
            | items ->  
                match List.tryFind (fun (i:CrateSet) ->  
                    match i.SmallestCrate() with  
                    | Some c when c > next -> true  
                    | _ -> false) items with  
                | None ->  
                    let cs = newCrateSet next  
                    items@[cs] // appending to the end is less efficient for linked lists, but ensures that the first one gets the best goodies  
                | Some crates ->  
                    if not (crates.Add(next)) then failwith "failed to add" // really wrong if this happens  
                    items  

        ) []  

let part1 () =  
    parseInput "Inputs/Quest03/Q03_P01.txt"  
    |> Enumerable.OrderDescending  
    |> packEfficiently  
    |> _.Max(_.Sum())  

let part2() =  
    parseInput "Inputs/Quest03/Q03_P02.txt"  
    |> Enumerable.Order  
    |> part2Impl  
    |> List.filter (fun x -> x.Count = 20)  
    |> _.Min(_.Sum())  
    
let part3() =  
    parseInput "Inputs/Quest03/Q03_P03.txt"  
    |> Enumerable.OrderDescending  
    |> packEfficiently  
    |> _.Count()  

I was scared of a hard combinatorial puzzle day, but this was a breeze.

{-# LANGUAGE TupleSections #-}
module Main (main) where
import Control.Monad ((<$!>))
import qualified Data.Text.IO as TextIO
import Data.Text (Text)
import qualified Data.Text as Text
import qualified Data.IntSet as IntSet
import Control.Arrow ((>>>))
import qualified Data.List as List
import qualified Data.IntMap as IntMap

part1 :: [IntSet.Key] -> IntSet.Key
part1 = IntSet.fromList
  >>> IntSet.foldl (+) 0

part2 :: [IntSet.Key] -> IntSet.Key
part2 = IntSet.fromList
  >>> IntSet.toAscList
  >>> take 20
  >>> sum

part3 :: [IntMap.Key] -> Int
part3 = List.map (, 1)
  >>> IntMap.fromListWith (+)
  >>> IntMap.toList
  >>> List.map snd
  >>> maximum

main :: IO ()
main = do
  sizes <- map (read . Text.unpack) . Text.split (== ',') <$!> TextIO.getLine
  print $ part1 sizes
  print $ part2 sizes
  print $ part3 sizes