标签：linked list two pointers leetcode
题目：
Given a linked list, return the node where the cycle begins. If there is no cycle, return null.
Follow up:
Can you solve it without using extra space?
思路：
可以参考
复杂度：O(N)
AC Code:
<span style="font-size:14px;">/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *detectCycle(ListNode *head) {
if(head == NULL || head->next == NULL) return NULL;
ListNode* fast = head;
ListNode* slow = head;
while(fast != NULL && fast->next != NULL)
{
slow = slow->next;
fast = fast->next->next;
if(slow == fast)
{
slow = head;
while(slow != fast)
{
slow = slow->next;
fast = fast->next;
}
return slow;
}
}
return NULL;
}
};</span>[C++]LeetCode: 73 Linked List Cycle II
标签：linked list two pointers leetcode
原文地址：http://blog.csdn.net/cinderella_niu/article/details/42490749
