Leetcode#141 Linked List Cycle

原题地址

经典链表题目，快慢指针法。曾经是面试热门题目之一，现在有些过时了。

代码：

bool hasCycle(ListNode *head) {
        ListNode *fast = head;
        ListNode *slow = head;
        bool running = false;
        
        while (fast && fast->next) {
            if (fast == slow && running)
                return true;
            running = true;
            fast = fast->next->next;
            slow = slow->next;
        }
        
        return false;
}