Highest/Maximum difference between two values in an array (HackerRank Task)

max-difference-array-elements.php

<?php
$a = [5, 10, 8, 7, 6, 5];

$size = sizeof($a)/sizeof($a[0]);

$max_diff = -1;

$min_element = $a[0];

for ($i=1; $i<$size; $i++) {
    
    if ($a[$i] > $min_element) {

         $diff = $a[$i] - $min_element;
         if ($diff > $max_diff) {
            $max_diff = $diff;
         }
      }
      else {
         $min_element = $a[$i];
      }
}