标签：
题目：
Given a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?
让head不断走一步，如果cur不为null，走两步，这样如果存在cycle，cur会追上head。
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: bool hasCycle(ListNode *head) { ListNode* cur = head; while (cur && cur->next != head){ cur = cur->next; if (cur) cur = cur->next; else break; head = head->next; } if (!cur) return false; return true; } };
［Leetcode］141. Linked List Cycle
标签：
原文地址：http://www.cnblogs.com/Doctengineer/p/5838647.html
