题解 | #判断链表中是否有环#

class Solution {
public:
bool hasCycle(ListNode *head) {
    if(!head || !head->next) return false;

    ListNode *low = head;
    ListNode *fast = head->next->next;

    while(low && fast){
        if(low == fast) return true;

        low = low->next;

        if(fast->next) fast = fast->next->next;
        else return false;
    }
    return false;

}

};