function getWaitingOrders($lwTime, $lwCustomerId, $lwOrderId, $upTime, $upCustomerId, $upOrderId, $count)
{
$params = buildParamsForGetOrders('time', $lwTime, $lwCustomerId, $lwOrderId, $upTime, $upCustomerId, $upOrderId);
$arrays = [];
$columns = ['order_id', 'customer_id', 'description', 'price', 'time'];
foreach (getAllDbsForWaitingOrders() as $dbInfo) {
$link = connect($dbInfo);
if (!$link) {
return null;
}
$elements = doGetOrders($link, 'waiting_orders', $columns, '', $count, $params);
if (is_null($elements)) {
return null;
}
array_push($arrays, $elements);
}
return mergeSortedArrays($arrays, false, false, function ($element) {
return $element['time'];
});
}
$heads = array_fill(0, count($arrays), 0);
$minHeap = new \SplMinHeap();
$result = [];
// Insert the first value from each sorted array into the min heap
for ($i = 0; $i < count($arrays); $i++) {
if (!empty($arrays[$i])) {
$minHeap->insert([$arrays[$i][0], $i]);
$heads[$i] = 1;
}
}
while (!$minHeap->isEmpty()) {
$smallestArray = $arrays[$minHeap->top()[1]];
$smallestHead = $heads[$minHeap->top()[1]];
$result[] = $minHeap->top()[0];
// If the smallest array has more values, put the next one into the heap
if ($smallestHead < count($smallestArray)) {
$minHeap->insert([$smallestArray[$smallestHead], $minHeap->top()[1]]);
$heads[$minHeap->top()[1]] += 1;
}
$minHeap->extract();
}
return $result;
}
$array1 = [1, 10, 20, 30];
$array2 = [1, 5, 10, 15];
$array3 = [2, 4, 8, 16];
$array4 = [3, 9, 27, 81];
$result = mergeSortedArrays([$array1, $array2, $array3, $array4]);
$result2 = mergeSortedArrays([]);
var_dump($result);
var_dump($result2);