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 myNewList = null;
        if (pHead1 == null) return pHead2;
        if (pHead2 == null) return pHead1;

        while (pHead1 != null || pHead2 != null) {
            if (pHead1 == null && pHead2 != null) {
                myNewList = insert(myNewList, pHead2);
                pHead2 = null;
                break;
            } else if (pHead1 != null && pHead2 == null) {
                myNewList = insert(myNewList, pHead1);
                pHead1 = null;
                break;
            }
            else if (pHead1.val <= pHead2.val) {
                ListNode temp = pHead1.next;
                pHead1.next = null;
                myNewList = insert(myNewList, pHead1);
                pHead1 = temp;
            } else {
                ListNode cur = pHead2.next;
                pHead2.next = null;
                myNewList = insert(myNewList, pHead2);
                pHead2 = cur;
            }
        }


        return myNewList;
    }

    public ListNode insert(ListNode myNewList, ListNode node) {
        if (myNewList == null) {
            myNewList = node;
            return myNewList;
        }

        ListNode cur = myNewList;
        while (cur.next != null) {
            cur = cur.next;
        }
        cur.next = node;

        return myNewList;
    }
}