文章作者:Tyan
博客:noahsnail.com | CSDN | 简书
1. Description
2. Solution
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *detectCycle(ListNode *head) {
if(!head) {
return nullptr;
}
ListNode* slow = head;
ListNode* fast = head;
while(true) {
if(fast == nullptr || fast->next == nullptr) {
return nullptr;
}
slow = slow->next;
fast = fast->next->next;
if(slow == fast) {
break;
}
}
slow = head;
while(slow != fast) {
slow = slow->next;
fast = fast->next;
}
return slow;
}
};