linked-list-cycle
/** * 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) { if(!head||!head->next) return false; ListNode *fast = head; ListNode *slow = head; while(fast && fast->next){ slow = slow->next; fast = fast->next->next; if(fast == slow) return true; } return false; } };
Given a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?