Advent of code(2024)(php): Day one

after accidentally starting 2022’s advent by mistake, here we are on 2024 day one.

The wording on this one confused the daylights out of me (I suppose part of the point of the challenges).

Part one was to take two columns of numbers sort them and sum the difference at each row.

Part two was to take each row from the left column times that by how often it appears in the right column then sum them together.

My advent repo

<?php
//$list = file("example_list.txt");
$list = file("input.txt");
$left = array();
$right = array();
$total_distance = 0;
$total_similarity = 0;
$part_one = 0;
$part_two = 0;
foreach ($list as $line){
    $line = explode("   ", $line);
    $left[] = $line[0];
    $right[] = $line[1];
}
sort($left);
sort($right);
foreach ($left as $index => $left_val){
    $index_distance = abs($left_val - $right[$index]);
    $total_distance = $total_distance + $index_distance;
    print("Index distance: " . $index_distance . "\n");
    print("Total distance: " . $total_distance . "\n");
    print("\n");
}

$part_one = $total_distance;

print("\npart one: " . $part_one . "\n\n");

foreach ($left as $index => $left_val){
    $similarity = $left_val * count(array_keys($right, $left_val));
    $total_similarity = $total_similarity + $similarity;
    print("Index similarity: " . $similarity . "\n");
    print("Total similarity: " . $total_similarity . "\n");
    print("\n");
}

$part_two = $total_similarity;

print("\npart two: " . $part_two . "\n\n");