let pq = new PriorityQueue();

for (let list of arrOfLists) {

  if (list) {

    let currentNode = list;

    pq.insert(currentNode.val);

​

    // process the rest of the list

    while (currentNode.next) {

      pq.insert(currentNode.next.val);

      currentNode = currentNode.next;

    }

  }

}

​

// returning this will return the head of the priority queue linked list result

return pq.first || [];