python 双指针
链表中环的入口结点
http://www.nowcoder.com/questionTerminal/253d2c59ec3e4bc68da16833f79a38e4
class Solution:
def EntryNodeOfLoop(self, pHead):
# write code here
if not pHead or not pHead.next:
return
slow = pHead
fast = pHead
while fast.next.next:
slow = slow.next
fast = fast.next.next
if slow == fast:
break
slow = pHead
while slow != fast:
slow = slow.next
fast = fast.next
return slow
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