【题目】{ 链接 }
/** * 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 * fast, *slow; fast = slow = head; while(fast && fast->next) { slow = slow->next; fast = fast->next->next; if(fast == slow) return true; } return false; } };