141. 环形链表c

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

结果：