elevator challenge solution

<?php
/**
 * Total stops
 * Execute the code at http://sandbox.onlinephpfunctions.com/code/98e0909b60bc2f1096961cc2a7be39efd7cab6cb
 * @param array $A people weights
 * @param array $B people destination floor
 * @param int   $M total floors
 * @param int   $X elevator's people capacity
 * @param int   $Y elevator's weight capacity
 * @return int total stops
 */
function solution($A, $B, $M, $X, $Y ) {
  $stops            = 0;
  $weight           = 0;
  $total_people     = 0;
  $elevator_travels = [];
  $travel_index     = 0;

  for($i = 0; $i < sizeof($A); $i++) {
    if($B[$i] > $M) {
      continue;
    }
    
    $total_people++;
    $weight += $A[$i];

    if($total_people > $X || $weight > $Y) {
      $travel_index++;
      $weight = 0;
      $total_people = 0;
    }

    $elevator_travels[$travel_index][$B[$i]] = 'visited'; // do not repeat floors
  }

  $stops += sizeof($elevator_travels); // total of returns to ground
  $stops += array_sum(array_map('sizeof', $elevator_travels)); // total of travels

  return $stops;
}
?>