题解 | #判断链表中是否有环#

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    // 快慢指针
    bool hasCycle(ListNode *head) {


        ListNode* fast = head;
        ListNode* low = head;
        while(fast && fast->next)
        {
            fast = fast->next->next;
            low = low->next;
            if(fast == low)
            {
                return true;
            }
            
        }

        return false;

    }
};