题解 | 合并两个排序的链表

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param pHead1 ListNode类
     * @param pHead2 ListNode类
     * @return ListNode类
     */
    public ListNode Merge (ListNode pHead1, ListNode pHead2) {
        // write code here
        ListNode dummy = new ListNode(1);
        ListNode ptr = dummy;
        PriorityQueue<ListNode> pq = new PriorityQueue<>((o1, o2)->o1.val - o2.val);
        if (pHead1 != null) pq.add(pHead1);
        if (pHead2 != null) pq.add(pHead2);

        while (!pq.isEmpty()) {
            ListNode curNode = pq.poll();
            if (curNode.next != null) {
                pq.add(curNode.next);
                curNode.next = null;
            }
            ptr.next = curNode;
            ptr = ptr.next;
        }
        return  dummy.next;
    }
}