循环链表

在这里插入代码片/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    bool hasCycle(ListNode *head) {
        ListNode* faster{head};
        ListNode* slower{head};
        if(head==NULL)
        return false;
        while(faster!=NULL&&faster->next!=NULL)
        {
            faster=faster->next->next;
            slower=slower->next;
            if(faster==slower)
            return true;
        }
        return false;
    }
};