Uiua

For entertainment purposes only, I’ll be trying a solution in Uiua each day until it all gets too much for me…

$ 3   4
$ 4   3
$ 2   5
$ 1   3
$ 3   9
$ 3   3
⊜∘⊸≠@\n     # Partition at \n.
⊜(⍆∵⋕)⊸≠@\s # Partition at space, parse ints, sort.

&p/+/(⌵-). # Part1 : Get abs differences, sum, print.

&p/+×⟜(/+⍉≡⌕)°⊂ # Part 2 : Count instances, mul out, sum, print.

Smalltalk

day1p12: input    
	| list1 list2 nums dist sim |
	
	list1 := OrderedCollection new.
	list2 := OrderedCollection new.
	
	input linesDo: [ :l |
		nums := l substrings collect: [ :n | n asInteger ].
		list1 add: (nums at: 1).
		list2 add: (nums at: 2).
	].

	list1 sort.
	list2 sort.
	
	dist := 0.
	list1 with: list2 do: [ :a :b | dist := dist + (a - b) abs ].
	
	sim := list1 sumNumbers: [ :x | x * (list2 occurrencesOf: x) ].
	
	^ Array with: dist with: sim.

Kotlin

No 💜 for Kotlin here?

import kotlin.math.abs

fun part1(input: String): Int {
    val diffs: MutableList<Int> = mutableListOf()
    val pair = parse(input)
    pair.first.sort()
    pair.second.sort()
    pair.first.forEachIndexed { idx, num ->
        diffs.add(abs(num - pair.second[idx]))
    }
    return diffs.sum()
}

fun part2(input: String): Int {
    val pair = parse(input)
    val frequencies = pair.second.groupingBy { it }.eachCount()
    var score = 0
    pair.first.forEach { num ->
        score += num * frequencies.getOrDefault(num, 0)
    }
    return score
}

private fun parse(input: String): Pair<MutableList<Int>, MutableList<Int>> {
    val left: MutableList<Int> = mutableListOf()
    val right: MutableList<Int> = mutableListOf()
    input.lines().forEach { line ->
        if (line.isNotBlank()) {
            val parts = line.split("\\s+".toRegex())
            left.add(parts[0].toInt())
            right.add(parts[1].toInt())
        }
    }
    return left to right
}

Viml

I think viml is a very fun language, i like weird languages lol, so this year im doing it in viml while trying to use as many of the original ed/ex commands as i can (:d, :p, :a, :g, …)

!cp ./puzzle1 ./puzzle1.editing
e ./puzzle1.editing

1,$sort
let row1 = []

g/^\d/let row1 = add(row1, str2nr(expand("<cword>"))) | norm 0dw
1d
1,$sort
g/^\d/execute 'norm cc' .. string(abs(expand("<cword>") - row1[line('.') - 1]))

$a|---ANSWER---
0
.
1,$-1g/^\d/call setline("$", str2nr(getline("$")) + str2nr(expand("<cword>")))

read ./puzzle1

let cnt = 0
g/^\d/let cnt += expand("<cword>") *
            \ searchcount(#{pattern: '\s\+' .. expand("<cword>")}).total

echo cnt .. "\n"

w! ./puzzle1.editing

Raku

I’m trying warm up to Raku again.

use v6;

sub MAIN($input) {
    my $file = open $input;

    grammar LocationList {
        token TOP { <row>+%"\n" "\n"* }
        token row { <left=.id> " "+ <right=.id> }
        token id { \d+ }
    }

    my $locations = LocationList.parse($file.slurp);
    my @rows = $locations<row>.map({ (.<left>.Int, .<right>.Int)});
    my $part-one-solution = (@rows[*;0].sort Z- @rows[*;1].sort)».abs.sum;
    say "part 1: $part-one-solution";

    my $rbag = bag(@rows[*;1].sort);
    my $part-two-solution = @rows[*;0].map({ $_ * $rbag{$_}}).sum;
    say "part 2: $part-two-solution";
}

I’m happy to see that Lemmy no longer eats Raku code.

TypeScript

import { AdventOfCodeSolutionFunction } from "./solutions";

function InstancesOf(sorted_array: Array<number>, value: number) {
    const index = sorted_array.indexOf(value);
    if(index == -1)
        return 0;

    let sum = 1;

    for (let array_index = index + 1; array_index < sorted_array.length; array_index++) {
        if(sorted_array[array_index] != value)
            break;

        sum += 1;
    }

    return sum;
}

export const solution_1: AdventOfCodeSolutionFunction = (input) => {
    const left: Array<number> = [];
    const right: Array<number> = [];

    const lines = input.split("\n");

    for (let index = 0; index < lines.length; index++) {
        const element = lines[index].trim();
        if(!element)
            continue;

        const leftRight = element.split("   ");
        left.push(Number(leftRight[0]));
        right.push(Number(leftRight[1]));
    }

    const numSort = (a: number, b: number) => a - b;
    left.sort(numSort);
    right.sort(numSort);

    let sum = 0;
    for (let index = 0; index < left.length; index++) {
        const leftValue = left[index];
        const rightValue = right[index];

        sum += Math.abs(leftValue - rightValue);
    }

    const part1 = `Part 1: ${sum}`;

    sum = 0;
    for (let index = 0; index < left.length; index++) {
        sum += left[index] * InstancesOf(right, left[index]);
    }

    const part2 = `Part 2: ${sum}`;

    return `${part1}\n${part2}`;
};

Haskell

Plenty of scope for making part 2 faster, but I think simple is best here. Forgot to sort the lists in the first part, which pushed me waaay off the leaderboard.

import Data.List

main = do
  [as, bs] <- transpose . map (map read . words) . lines <$> readFile "input01"
  print . sum $ map abs $ zipWith (-) (sort as) (sort bs)
  print . sum $ map (\a -> a * length (filter (== a) bs)) as

Go

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func main() {
	input, _ := os.Open("input.txt")
	defer input.Close()

	left, right := []int{}, []int{}

	scanner := bufio.NewScanner(input)
	for scanner.Scan() {
		line := scanner.Text()
		splitline := strings.Split(line, "   ")
		l, _ := strconv.Atoi(splitline[0])
		r, _ := strconv.Atoi(splitline[1])
		left, right = append(left, l), append(right, r)
	}

	fmt.Printf("part 1 - total diff: %d\n", part1(left, right))
	fmt.Printf("part 2 - new total: %d\n", part2(left, right))
}

func part1(left, right []int) int {
	diff := 0
	sort.Ints(left)
	sort.Ints(right)

	for i, l := range left {
		if l > right[i] {
			diff += (l - right[i])
		} else {
			diff += (right[i] - l)
		}
	}
	return diff
}

func part2(left, right []int) int {
	newTotal := 0

	for _, l := range left {
		matches := 0
		for _, r := range right {
			if l == r {
				matches++
			}
		}
		newTotal += l * matches
	}
	return newTotal
}

python

I didn’t realize it was december until this afternoon. I’ve generally chosen a new or spartan lang to challenge myself, but I’m going easy mode this year with python and just focusing on meeting the requirement.

import aoc

def setup():
    lines = aoc.get_lines(1)
    l = [int(x.split()[0]) for x in lines]
    r = [int(x.split()[1]) for x in lines]
    return (l, r, 0)

def one():
    l, r, acc = setup()
    for p in zip(sorted(l), sorted(r)):
        acc += abs(p[0] - p[1])
    print(acc)

def two():
    l, r, acc = setup()
    for n in l:
        acc += n * r.count(n)
    print(acc)

one()
two()

I’m late to the party, as usual. Damned timezones. This year I’m going to tackle with a small handful of languages, but primarily Elixir and Gleam. This is my first time trying this languages in earnest, so expect some terrible, inefficient and totally unidiomatic code!
Here’s day one:

Elixir

part_one =
  File.read!("input.in")
  |> String.split("\n", trim: true)
  |> Enum.map(fn line ->
    line
    |> String.split()
    |> Enum.map(&String.to_integer/1)
  end)
  |> Enum.reduce({[], []}, fn [first, second], {list1, list2} ->
    {[first | list1], [second | list2]}
  end)
  |> then(fn {list1, list2} ->
    {Enum.sort(list1), Enum.sort(list2)}
  end)
  |> then(fn {list1, list2} ->
    Enum.zip(list1, list2)
    |> Enum.map(fn {x, y} -> abs(x - y) end)
  end)
  |> Enum.sum()

part_two =
  File.read!("input.in")
  |> String.split("\n", trim: true)
  |> Enum.map(fn line ->
    line
    |> String.split()
    |> Enum.map(&String.to_integer/1)
  end)
  |> Enum.reduce({[], []}, fn [first, second], {list1, list2} ->
    {[first | list1], [second | list2]}
  end)
  |> then(fn {list1, list2} ->
    Enum.map(list1, fn line ->
      line * Enum.count(list2, fn x -> x === line end)
    end)
    |> Enum.sum()
  end)

IO.inspect(part_one)
IO.inspect(part_two)

Elixir

Total noob, but it’s fun to learn.

{left, right} =
  File.read!("./input.txt")
  |> String.split("\n", trim: true)
  |> Enum.map(fn line ->
    String.split(line)
    |> Enum.map(&String.to_integer/1)
    |> List.to_tuple()
  end)
  |> Enum.unzip()
  |> then(fn {left, right} ->
    {Enum.sort(left), Enum.sort(right)}
  end)

diffs =
  Enum.zip(left, right)
  |> Enum.map(fn {l, r} -> abs(l - r) end)
  |> Enum.sum()

freqs =
  Enum.filter(right, fn r -> r in left end)
  |> Enum.frequencies()

freqsum =
  Enum.map(left, fn n ->
    freq = Map.get(freqs, n, 0)
    n * freq
  end)
  |> Enum.sum()

IO.puts("part 1: #{diffs}")
IO.puts("part 2: #{freqsum}")

Zig

const std = @import("std");
const List = std.ArrayList;
const Map = std.AutoHashMap;

const splitSeq = std.mem.splitSequence;
const splitScalar = std.mem.splitScalar;
const parseInt = std.fmt.parseInt;
const print = std.debug.print;
const sort = std.sort.block;

var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const alloc = gpa.allocator();

const Answer = struct {
    distance: u32,
    similarity: u32,
};

fn lessThan(_: void, lhs: []const u8, rhs: []const u8) bool {
    return std.mem.lessThan(u8, lhs, rhs);
}

pub fn solve(input: []const u8) !Answer {
    var rows = splitScalar(u8, input, '\n');
    var left_list = List([]const u8).init(alloc);
    defer left_list.deinit();
    var right_list = List([]const u8).init(alloc);
    defer right_list.deinit();

    // PART 1

    // split the rows into two lists
    while (rows.next()) |row| {
        var sides = splitSeq(u8, row, "   ");
        try left_list.append(sides.next() orelse break);
        try right_list.append(sides.next() orelse break);
    }
    _ = left_list.pop(); // last null

    // sort both lists
    sort([]const u8, left_list.items, {}, lessThan);
    sort([]const u8, right_list.items, {}, lessThan);

    var distance: u32 = 0;
    for (left_list.items, right_list.items) |left, right| {
        distance += @abs(try parseInt(i32, left, 10) - try parseInt(i32, right, 10));
    }

    // PART 2
    var right_scores = Map(i32, u32).init(alloc);
    defer right_scores.deinit();

    // count number of item appearances in the right list
    for (right_list.items) |item| {
        const value = try parseInt(i32, item, 10);
        const result = try right_scores.getOrPut(value);
        if (!result.found_existing) {
            result.value_ptr.* = 1;
        } else {
            result.value_ptr.* += 1;
        }
    }

    // sum up similarity between items in left list and right list scores
    var similarity: u32 = 0;
    for (left_list.items) |item| {
        const value = try parseInt(i32, item, 10);
        const result = right_scores.get(value) orelse 0;
        similarity += @as(u32, @intCast(value)) * result;
    }
    return Answer{ .distance = distance, .similarity = similarity };
}

pub fn main() !void {
    const answer = try solve(@embedFile("input.txt"));
    print("Part 1: {d}\n", .{answer.distance});
    print("Part 2: {d}\n", .{answer.similarity});
}

test "test input" {
    const answer = try solve(@embedFile("test.txt"));
    try std.testing.expectEqual(answer.distance, 11);
    try std.testing.expectEqual(answer.similarity, 31);
}

Factor

: get-input ( -- left-list right-list )
  "vocab:aoc-2024/01/input.txt" utf8 file-lines
  [ split-words harvest ] map unzip
  [ [ string>number ] map ] bi@ ;

: part1 ( -- n )
  get-input
  [ sort ] bi@
  [ - abs ] 2map-sum ;

: part2 ( -- n )
  get-input
  histogram
  '[ dup _ at 0 or * ] map-sum ;

https://github.com/AndydeCleyre/aoc-2024

Elixir

defmodule AdventOfCode.Solution.Year2024.Day01 do
  use AdventOfCode.Solution.SharedParse

  @impl true
  def parse(input) do
    numbers =
      input
      |> String.split("\n", trim: true)
      |> Enum.map(fn l -> String.split(l, ~r/\s+/) |> Enum.map(&String.to_integer/1) end)

    {Stream.map(numbers, &Enum.at(&1, 0)), Stream.map(numbers, &Enum.at(&1, 1))}
  end

  def part1({left, right}) do
    Enum.zip_reduce(Enum.sort(left), Enum.sort(right), 0, &(&3 + abs(&1 - &2)))
  end

  def part2({left, right}) do
    freq = Enum.frequencies(right)
    left |> Stream.map(&(&1 * Map.get(freq, &1, 0))) |> Enum.sum()
  end
end

Python

ids = """<multiline input string>"""
ids = [pair.split(" ") for pair in ids.split("\n")]
left = [int(t[0]) for t in ids]
right = [int(t[-1]) for t in ids]
left.sort()
right.sort()
print(sum(abs(l - r) for l, r in zip(left, right)))

# 2
s = 0
for l in left:
    s += right.count(l) * l
print(s)

Lost a minute because I forgot about abs .-.