Day 25: Code Chronicle

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FAQ

3 points

Uiua

A Christmas Day treat: a one-liner for you all to decipher!

"#####\n.####\n.####\n.####\n.#.#.\n.#...\n.....\n\n#####\n##.##\n.#.##\n...##\n...#.\n...#.\n.....\n\n.....\n#....\n#....\n#...#\n#.#.#\n#.###\n#####\n\n.....\n.....\n#.#..\n###..\n###.#\n###.#\n#####\n\n.....\n.....\n.....\n#....\n#.#..\n#.#.#\n#####"
/+β™­βŠž(/Γ—<8+)βˆ©Β°β–‘Β°βŠŸ βŠ•(░≑≑/+βŒ•@#)β‰ @#≑(⊒⊒). ⊜(β‰βŠœβˆ˜βŠΈβ‰ @\n)¬±⦷"\n\n". 
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3 points

Kotlin

A fun and small challenge. First read all locks, transpose their profile and count the #s (-1 for the full row). Then do the same for the keys.

Lastly find all keys for all locks that do not sum to more than 5 with their teeth:

Code

val lockRegex = Regex("""#{5}(\r?\n[.#]{5}){6}""")
val keyRegex = Regex("""([.#]{5}\r?\n){6}#{5}""")

fun parseLocksAndKeys(inputFile: String): Pair<List<IntArray>, List<IntArray>> {
    val input = readResource(inputFile)
    val locks = lockRegex
        .findAll(input)
        .map {
            it
                .value
                .lines()
                .map { line -> line.toList() }
                .transpose()
                .map { line -> line.count { c -> c == '#' } - 1 }
                .toIntArray()
        }
        .toList()

    val keys = keyRegex
        .findAll(input)
        .map {
            it
                .value
                .lines()
                .map { line -> line.toList() }
                .transpose()
                .map { line -> line.count { c -> c == '#' } - 1 }
                .toIntArray()
        }
        .toList()

    return locks to keys
}

fun part1(inputFile: String): String {
    val (locks, keys) = parseLocksAndKeys(inputFile)

    val matches = locks.map { lock ->
        keys.filter { key ->
            for (i in lock.indices) {
                // Make sure the length of the key and lock do not exceed 5
                if (lock[i] + key[i] > 5) {
                    return@filter false
                }
            }
            true
        }
    }
        .flatten()
        .count()

    return matches.toString()
}

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4 points
*

Dart

Quick and dirty, and slightly tipsy, code.

Happy Christmas everyone!

Thanks to Eric and the team at Advent of Code, to @Ategon@programming.dev and @CameronDev@programming.dev for giving us somewhere to share and discuss our solutions, and to everyone here for the friendly and supportive community.

See you all next year!

import 'package:collection/collection.dart';
import 'package:more/more.dart';

part1(List<String> lines) {
  var (w, h) = (lines.first.length, lines.indexOf(''));
  var (falsey: keys, truthy: locks) = (lines..insert(0, ''))
      .splitBefore((l) => l.isEmpty)
      .map((g) => [
            for (var x in 0.to(w)) [for (var y in 1.to(h + 1)) g[y][x]]
          ])
      .partition((g) => g[0][0] == '#');
  return keys
      .map((l) => locks.count((k) =>
          0.to(w).every((r) => (l[r] + k[r]).count((e) => e == '#') < 8)))
      .sum;
}
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3 points

Haskell

Merry Christmas!

{-# LANGUAGE OverloadedStrings #-}

module Main where

import Data.Either
import Data.Text hiding (all, head, zipWith)
import Data.Text qualified as T
import Data.Text.IO as TIO

type Pins = [Int]

toKeyLock :: [Text] -> Either Pins Pins
toKeyLock v = (if T.head (head v) == '#' then Left else Right) $ fmap (pred . count "#") v

solve keys locks = sum [1 | k <- keys, l <- locks, fit k l]
  where
    fit a b = all (<= 5) $ zipWith (+) a b

main = TIO.getContents >>= print . uncurry solve . partitionEithers . fmap (toKeyLock . transpose . T.lines) . splitOn "\n\n"
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2 points

Rust

Nice ending for this year. Lock and key arrays are just added together and all elements must be <= 5. Merry Christmas!

Solution
fn flatten_block(block: Vec<Vec<bool>>) -> [u8; 5] {
    let mut flat = [0; 5];
    for row in &block[1..=5] {
        for x in 0..5 {
            if row[x] {
                flat[x] += 1;
            }
        }
    }
    flat
}

fn parse(input: &str) -> (Vec<[u8; 5]>, Vec<[u8; 5]>) {
    let mut locks = Vec::new();
    let mut keys = Vec::new();
    for block_s in input.split("\n\n") {
        let block: Vec<Vec<bool>> = block_s
            .lines()
            .map(|l| l.bytes().map(|b| b == b'#').collect::<Vec<bool>>())
            .collect();
        assert_eq!(block.len(), 7);
        // Lock
        if block[0].iter().all(|e| *e) {
            locks.push(flatten_block(block));
        } else {
            keys.push(flatten_block(block));
        }
    }
    (locks, keys)
}

fn part1(input: String) {
    let (locks, keys) = parse(&input);
    let mut count = 0u32;
    for l in locks {
        for k in &keys {
            if l.iter().zip(k).map(|(li, ki)| li + ki).all(|sum| sum <= 5) {
                count += 1;
            }
        }
    }
    println!("{count}");
}

fn part2(_input: String) {
    println!("⭐");
}

util::aoc_main!();

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