1 # -*- coding:utf-8 -*-
2 # class ListNode:
3 # def __init__(self, x):
4 # self.val = x
5 # self.next = None
6 """首先判断长度，然后移动指针将两个链表尾部对齐，当两链表的头指针相等时，即为交点"""
7 class Solution:
8 def FindFirstCommonNode(self, pHead1, pHead2):
9 # write code here
10 if pHead1==None or pHead2==None:
11 return None
12 la=self.len_list(pHead1)
13 lb=self.len_list(pHead2)
14 if la>lb:
15 i=0
16 while i<la-lb:
17 pHead1= pHead1.next
18 i+=1
19 if la<lb:
20 i=0
21 while i<la-lb:
22 pHead2= pHead2.next
23 i+=1
24 while pHead1!=pHead2:
25 pHead1= pHead1.next
26 pHead2= pHead2.next
27 return pHead1
28 def len_list(self,Head): #定义一个新的方法也是要先判断极端情况
29 if Head==None:
30 return None
31 count=0
32 while Head: #head肯定不是none,已经判断了上面，
33 Head=Head.next
34 count+=1
35 return count
36
