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Given a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?
题意:判断一个链表中是否有环
思路:快慢指针,如果有环,最终快慢指针会在非NULL相遇
注:用到fast->next前先要确保fast非NULL,要用fast->next->next前先要确保fast,fast->next非NULL
复杂度:时间O(n), 空间O(1)
相关题目:Linked List CycleII/** * 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){ fast = fast->next->next; slow = slow->next; if(fast == slow) return true; } return false; }
Leetcode 线性表 Linked List Cycle,布布扣,bubuko.com
Leetcode 线性表 Linked List Cycle
标签:style blog class code c tar
原文地址:http://blog.csdn.net/zhengsenlie/article/details/25721437