141. Linked List Cycle（C语言版本）

Given a linked list, determine if it has a cycle in it.

Follow up:

Can you solve it without using extra space?

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     struct ListNode *next; * }; */bool hasCycle(struct ListNode *head) {    struct ListNode *fast,*slow;    fast = slow = head;    while( slow && fast && fast->next ){        fast=fast->next->next;        slow=slow->next;        if(fast==slow) return true;    }    return false;}