【LC】环形链表

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题目描述：

题解：

class Solution {
public:
    bool hasCycle(ListNode *head) {
        if(head == nullptr) return false;
        ListNode* slow = head;
        ListNode* fast = head;

        while(fast != nullptr && fast->next != nullptr)
        {
            slow = slow->next;
            fast = fast->next->next;
            if(slow == fast)
            {
                return true;
            }
        }
        return false;
    }
};