LeetCode -- Intersection of Two Linked Lists

Write a program to find the node at which the intersection of two singly linked lists begins.

For example, the following two linked lists:

A:          a1 → a2
↘
c1 → c2 → c3
↗
B:     b1 → b2 → b3

begin to intersect at node c1.

Notes:

If the two linked lists have no intersection at all, return

null

.
The linked lists must retain their original structure after the function returns.
You may assume there are no cycles anywhere in the entire linked structure.

Your code should preferably run in O(n) time and use only O(1) memory.

两个链表，有可能交叉，如果有的话要返回节点。
在这里搞了很久，因为没看清题目，，以为会出现X这种形状。
总之，，两个链表如果有交点的话，，他们的最后必须是一样的

代码：

# Definition for singly-linked list.
class ListNode:
def __init__(self, x):
self.val = x
self.next = None

class Solution:
# @param two ListNodes
# @return the intersected ListNode
def getIntersectionNode(self, headA, headB):
curA,curB = headA,headB
lenA,lenB = 0,0
while curA is not None:
lenA += 1
curA = curA.next
while curB is not None:
lenB += 1
curB = curB.next
curA,curB = headA,headB
if lenA > lenB:
for i in range(lenA-lenB):
curA = curA.next
elif lenB > lenA:
for i in range(lenB-lenA):
curB = curB.next
while curB != curA:#能这么写是因为他们的交点是同一个对象，用的是同一个内存位置
print curB.val
curB = curB.next
print curA.val
curA = curA.next
return curA