PHP web crawler, check URL for path - php

Question

I'm writing a simple web crawler to grab some links from a site.
I need to check the returned links to make sure I selectively collect what I want.
For example, here's a few links returned from http://www.polygon.com/
[0] http://www.polygon.com/2015/5/15/8613113/destiny-queens-wrath-bounties-ether-key-guide#comments
[1] http://www.polygon.com/videos
[2] http://www.polygon.com/2015/5/15/8613113/destiny-queens-wrath-bounties-ether-key-guide
[3] http://www.polygon.com/features
so link 0 and 2 are links I want to grab, 1 and 3 we don't want. there's an obvious visual distinction between the links so how would I compare them?
How would I check to make sure I don't return 1 and 3? ideally i'd like to be able to input something so it could adapt to any site.
I was thinking I need to check the link to make sure its past /2015/ etc but I'm pretty lost.
here's the PHP code i'm using to grab links:
<?php
$source_url = 'http://www.polygon.com/';
$html = file_get_contents($source_url);
$dom = new DOMDocument;
#$dom->loadHTML($html);
$links = $dom->getElementsByTagName('a');
foreach ($links as $link) {
$input_url = $link->getAttribute('href');
echo $input_url . "<br>";
}
?>

Answer 1

It looks like regular expressions would be helpful here.
You could say, for instance:
/* if $input_url contains a 4 digit year, slash, number(s), slash, number(s) */
if (preg_match("/\/20\d\d\/\d+\/\d+\/",$input_url)) {
echo $input_url . "<br>";
}