Advent of Code 2023 - day 1

day1.php

<?php
declare(strict_types=1);

$input = file('input.txt', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
$sumOfNumbers = 0;
foreach ($input as $line) {
    printf('turned %s into ', $line);
    $line = replaceNumberWordsWithDigits($line);
    printf('%s' . PHP_EOL, $line);
    $digits = getFirstAndLastDigitsFromLine($line);
    $number = intval($digits[0] . $digits[1]);
    $sumOfNumbers += $number;
}

printf('The total sum of all numbers is: %s' . PHP_EOL, $sumOfNumbers);

function getFirstAndLastDigitsFromLine(string $line): array
{
    $justDigits = preg_replace('/[^0-9]/', '', $line);
    if (strlen($justDigits) < 1) {
        throw new RuntimeException(sprintf('er is niets over van regel %s' . PHP_EOL, $line));
    }
    
    return [
        substr($justDigits, 0, 1),
        substr($justDigits, -1),
    ];
}

function replaceNumberWordsWithDigits(string $line): string
{
    //this is just plain evil :(
    $line = str_replace(
        ['oneight', 'threeight', 'fiveight', 'nineight', 'twone', 'threeight', 'fiveight', 'sevenine', 'eightwo', 'eighthree', ],
        ['18', '38', '58', '98', '21', '38', '58', '79', '82', '83', ],
        $line
    );
    
    $line = str_replace(
        ['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine'],
        ['1', '2', '3', '4', '5', '6', '7', '8', '9'],
        $line
    );
    
    return $line;
}