Solves Advent of code puzzle 4 though brute force. May output the solution to the first challenge multiple times.

aoc-4.php

<?php
$match5 = 0;
$match6 = 0;
$i = 0;
$salt = 'yzbqklnj';

while ( '000000' !== $match6 ) {
	$i++;
	$hash = md5( $salt . $i );
	$match5 = substr( $hash, 0, 5 );
	$match6 = substr( $hash, 0, 6 );
	if ( '00000' === $match5 ) {
		echo 'answer 1: ' . $i . "\n";
	}
}
echo 'answer: ' . $i;