$re = '/.*(https:\/\/cloud\.saikoanimes\.net\/.*)" c.*/m';
$str = '
<a href="https://cloud.saikoanimes.net/11Yu" class="btn-sa" target="blank">01</a>
<a href="https://cloud.saikoanimes.net/BXz" class="btn-sa" target="blank">02</a>
<a href="https://cloud.saikoanimes.net/BXv" class="btn-sa" target="blank">03</a>
<a href="https://cloud.saikoanimes.net/11Yx" class="btn-sa" target="blank">04</a>
<a href="https://cloud.saikoanimes.net/BXt" class="btn-sa" target="blank">05</a>
<a href="https://cloud.saikoanimes.net/BXw" class="btn-sa" target="blank">06</a>
<a href="https://cloud.saikoanimes.net/11Yv" class="btn-sa" target="blank">07</a>
<a href="https://cloud.saikoanimes.net/BXx" class="btn-sa" target="blank">08</a>
<a href="https://cloud.saikoanimes.net/BXy" class="btn-sa" target="blank">09</a>
<a href="https://cloud.saikoanimes.net/11Yo" class="btn-sa" target="blank">10</a>
<a href="https://cloud.saikoanimes.net/11Ym" class="btn-sa" target="blank">11</a>
<a href="https://cloud.saikoanimes.net/11Yw" class="btn-sa final" target="blank">12</a> ';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php