1 /** 2 * Definition for singly-linked list. 3 * struct ListNode { 4 * int val; 5 * ListNode *next; 6 * ListNode(int x) : val(x), next(NULL) {} 7 * }; 8 */ 9 class Solution { 10 public: 11 ListNode *detectCycle(ListNode *head) { 12 if (!head || !head->next) return NULL; 13 ListNode *slow = head, *fast = head; 14 bool flag = false; 15 while (fast && fast->next) { 16 slow = slow->next; 17 fast = fast->next->next; 18 if (slow == fast) { 19 flag = true; 20 break; 21 } 22 } 23 if (!flag) return NULL; 24 fast = head; 25 while (slow != fast) { 26 slow = slow->next; 27 fast = fast->next; 28 } 29 return slow; 30 } 31 };
时间: 2024-10-05 06:05:29