【leetcode】23. 合并K个升序链表

class Solution {
    public ListNode mergeKLists(ListNode[] lists) {
        if (lists.length == 0) {
            return null;
        }
        ListNode head = new ListNode(0);
        ListNode curr = head;
        PriorityQueue<ListNode> pq = new PriorityQueue<>(Comparator.comparingInt(o -> o.val));
        for (ListNode list : lists) {
            if (list == null) {
                continue;
            }
            pq.add(list);
        }
        while(!pq.isEmpty()) {
            ListNode nextNode = pq.poll();
            curr.next = nextNode;
            curr = curr.next;
            if (nextNode.next != null) {
                pq.add(nextNode.next);
            }
        }
        return head.next;
    }
}