ValidPasscodes.php

<?php

namespace App\Services;

use App\Match;
use App\Range;

class Digits
{
    public static function calculate()
    {
        ini_set('max_execution_time', 560);
        set_time_limit(0);
        $ranges = Range::where('done', 0)->take(5)->get();

        foreach ($ranges as $range) {
            $validPasscodes = 0;
            for ($firstNumber = $range->start; $firstNumber <= $range->end; $firstNumber++) {
                // Number is a 6 digit numeric passcode
                if ($firstNumber > 999999) {
                    continue;
                }

                // check for repeating digits
                // check for decreasing integer
                $repeatingDigits = 0;
                $decreasingDigits = 0;
                $digits = str_split($firstNumber);
                for ($i = 0; $i < strlen($firstNumber) - 1; $i++) {
                    $x = $i + 1;
                    if ((int)$digits[$i] == (int)$digits[$x]) {
                        $repeatingDigits++;
                    }

                    if ((int)$digits[$i] > (int)$digits[$x]) {
                        $decreasingDigits++;
                    }
                }

                if ($repeatingDigits == 0 || $decreasingDigits !== 0) {
                    continue;
                }
                $validPasscodes++;
                Match::create([
                    'range_id' => $range->id,
                    'match' => $firstNumber
                ]);
            }

            $range->num_valid = $validPasscodes;
            $range->done = 1;
            $range->save();
        }

    }
}