题解 | #链表中环的入口结点#
链表中环的入口结点
https://www.nowcoder.com/practice/253d2c59ec3e4bc68da16833f79a38e4
/* struct ListNode { int val; struct ListNode *next; ListNode(int x) : val(x), next(NULL) { } }; */ class Solution { public: ListNode* EntryNodeOfLoop(ListNode* head) { ListNode* slow = head; ListNode* fast = head; while(slow && fast) { slow = slow->next; if(fast->next) fast=fast->next->next; if(slow == fast) break; } if(fast == NULL || fast->next == NULL) return NULL; fast = head; while(fast != slow) { fast=fast->next; slow = slow->next; } return fast; } };