剑指Offer 25 合并两个排序的链表

输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。

 1 # -*- coding:utf-8 -*-
 2 # class ListNode:
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.next = None
 6 class Solution:
 7     # 返回合并后列表
 8     def Merge(self, pHead1, pHead2):
 9         if pHead1 == None:
10             return pHead2
11         if pHead2 == None:
12             return pHead1
13         if pHead1.val <= pHead2.val:
14             pHead1.next = self.Merge(pHead1.next,pHead2)
15             return pHead1
16         else:
17             pHead2.next = self.Merge(pHead1,pHead2.next)
18             return pHead2
19         # write code here