🌟 Advent of Code (AoC) 2024 🌟

d←↓⍉↑⍎¨⊃⎕NGET'1.txt'1
+/|-⌿↑(⊂∘⍋⌷⊢)¨d  ⍝ del1    
{+/⍺×+/⍺∘.=⍵}/d    ⍝ del2

Using
   .resource(Source.fromFile(path))(_.getLines.toArray)
   .map(_.split("   ").map(_.toInt))
   .transpose
   .map(_.sortInPlace())
   .pipe:
      case Array(fst, snd) =>
         println(s"del1: ${fst.zip(snd).map((x, y) => (x - y).abs).sum}")
         println(s"del2: ${fst.foldLeft(0)((acc, x) => acc + x * snd.count(_ == x))}")

use std::{collections::HashMap, error::Error};

fn main() -> Result<(), Box<dyn Error>> {
    let content = std::fs::read_to_string("input.txt")?;
    let content: Vec<_> = content
        .lines()
        .flat_map(|line| {
            line.split_ascii_whitespace()
                .filter_map(|s| s.parse::<u32>().ok())
                .collect::<Vec<_>>()
        })
        .collect();

    let transposed = transpose(content);
    part1(&transposed);
    part2(&transposed);
    Ok(())
}

fn transpose(content: Vec<u32>) -> Vec<Vec<u32>> {
    let mut result = vec![vec![]; 2];
    for chunk in content.chunks(2) {
        (0..chunk.len()).for_each(|index| result[index].push(chunk[index]));
    }
    result.iter_mut().for_each(|v| v.sort());
    result
}

fn part1(input: &Vec<Vec<u32>>) {
    let mut sum = 0;
    for i in 0..input.first().map(|v| v.len()).unwrap_or_default() {
        sum += input.iter().fold(0, |accum, v| v[i].abs_diff(accum));
    }
    println!("{sum}");
}

fn part2(input: &Vec<Vec<u32>>) {
    let right: HashMap<u32, u32> = input[1].iter().fold(HashMap::new(), |mut accum, key| {
        *accum.entry(*key).or_default() += 1;
        accum
    });
    println!(
        "{}",
        input[0].iter().fold(0, |accum, value| {
            accum + value * right.get(value).unwrap_or(&0)
        })
    );
}

<?php
// All data which is a tuple of two numbers separated by 3 spaces
$data = "88159   51481
66127   31794
71500   84893
and_so_on..."; // Data from: https://adventofcode.com/2024/day/1/input

// We create a lines array
$lines = explode("\n", $data);

// Now we will extract each number from each line, one number
// is to the left of 3 spaces and the other is to the right
// We also convert the string numbers to integers while we're at it
$leftArr = [];
$rightArr = [];

foreach ($lines as $line) {
    $numbers = explode("   ", $line);
    $leftArr[] = intval($numbers[0]);
    $rightArr[] = intval($numbers[1]);
}

// We will now sort each array in ascending order
sort($leftArr);
sort($rightArr);

// We will now loop through both arrays at the same time and
// add the difference between the two numbers to a sum
$sumOfDifferenceBetweenTheTwoArrays = 0;

// Using "abs" we can find the absolute value of the difference
for ($i = 0; $i < count($leftArr); $i++) {
    $sumOfDifferenceBetweenTheTwoArrays += abs($leftArr[$i] - $rightArr[$i]);
}

// Output the sum of the differences between the two arrays
echo $sumOfDifferenceBetweenTheTwoArrays;
?>

<?php
// All data which is a tuple of two numbers separated by 3 spaces
$data = "88159   51481
66127   31794
and_so_on..."; // Source: https://adventofcode.com/2024/day/1/input
// We create a lines array
$lines = explode("\n", $data);

// Now we will extract each number from each line, one number
// is to the left of 3 spaces and the other is to the right
// We also convert the string numbers to integers while we're at it
$leftArr = [];
$rightArr = [];
$leftArr2 = [];
$rightArr2 = [];

foreach ($lines as $line) {
    $numbers = explode("   ", $line);
    $leftArr[] = intval($numbers[0]);
    $rightArr[] = intval($numbers[1]);
}

// Also store in a separate array for later Part 2
$leftArr2 = $leftArr;
$rightArr2 = $rightArr;

// We will now sort each array in ascending order
sort($leftArr);
sort($rightArr);

// We will now loop through both arrays at the same time and
// add the difference between the two numbers to a sum
$sumOfDifferenceBetweenTheTwoArrays = 0;

// Using "abs" we can find the absolute value of the difference
for ($i = 0; $i < count($leftArr); $i++) {
    $sumOfDifferenceBetweenTheTwoArrays += abs($leftArr[$i] - $rightArr[$i]);
}

// Output the sum of the differences between the two arrays
echo $sumOfDifferenceBetweenTheTwoArrays;

// Here in Part 2 we will use the two arrays again. We begin by
// counting the values in right array by using array_count_values.
// We will then loop through the left array and if we find its value
// as a key in the righytArrayCount array then we will check if it
// exists in the foundKeysFromRightArr array. If it does not exist
// then we will add it and we will multiply the found key with the
// corresponding key in the rightArrayCount array (it's value) and
// add that to the $similarityScore. After looping through all the
// values in the left array we will output the $similarityScore.
$rightArrCount = array_count_values($rightArr2);
$foundKeysFromRightArr = [];
$similarityScore = 0;
$length = count($leftArr2); // Jag la till $length för att inte plåga sönder for-loopen! :P

for ($i = 0; $i < $length; $i++) {
    if (array_key_exists($leftArr2[$i], $rightArrCount)) {
        if (!in_array($leftArr2[$i], $foundKeysFromRightArr)) {
            $foundKeysFromRightArr[] = $leftArr2[$i];
            $similarityScore += $leftArr2[$i] * $rightArrCount[$leftArr2[$i]];
        }
        // The "else" is when key has already been added, then we only need to add the value
        // that is already in the foundKeysFromRightArr array
        else {
            $similarityScore += $leftArr2[$i];
        }
    }
}

echo "\n" . $similarityScore;
?>

def p1():
    with open('input.txt', 'r') as file:
        lines = [line.strip().split() for line in file]
        l1 = sorted(int(line[0]) for line in lines)
        l2 = sorted(int(line[1]) for line in lines)
        res = sum(abs(id1 - id2) for id1, id2 in zip(l1, l2))
    print(res)

def p2():
    with open('input.txt', 'r') as file:
        lines = [line.strip().split() for line in file]
        l1 = sorted(int(line[0]) for line in lines)
        l2 = {}
        for line in lines:
            key = int(line[1])
            l2[key] = l2.get(key, 0) + key
        
        res = sum(l2.get(id, 0) for id in l1)
    print(res)

p1()
p2()

library(tidyverse)

dat <- readLines("2024/1/input.txt")[-1] %>% str_split("\\s+") %>% map(as.numeric)

v1 <- v %>% map(~.x[1]) %>% unlist()
v2 <- v %>% map(~.x[2]) %>% unlist()

# part1
sum(abs(sort(v1)-sort(v2)))

# part2
tibble(a=v1, b=v2) %>%
  rowwise() %>%
  mutate(aib = sum(v2 %in% a),
         sim = a*aib) %>%
  ungroup() %>%
  summarise(s=sum(sim))