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
        if(pHead1 == null && pHead2 == null)return null;
        List<Integer> list = new ArrayList<>();

        while (pHead1 != null && pHead2 != null) {
            int num1 = pHead1.val;
            int num2 = pHead2.val;
            if (num1 <= num2) {
                list.add(num1);
                pHead1 = pHead1.next;
            }else{
                list.add(num2);
                pHead2 = pHead2.next;
            }
        }

        while (pHead1 != null) {
            list.add(pHead1.val);
            pHead1 = pHead1.next;
        }

        while (pHead2 != null) {
            list.add(pHead2.val);
            pHead2 = pHead2.next;
        }

        ListNode newNode = new ListNode(list.get(0));
        ListNode cur = newNode;

        for(int i = 1; i < list.size(); i++){
            ListNode next = new ListNode(list.get(i));
            cur.next = next;
            cur = next;
        }

        return newNode;
    }
}