代码随想录第十二天

链表-环形链表II

题目链接

这道题感觉还是有点难，看了这篇题解觉得很清楚详细。其实代码很简单，理清楚逻辑很重要。

 struct ListNode *detectCycle(struct ListNode *head) {
    typedef struct ListNode ListNode;
    ListNode* fast = head;
    ListNode* slow = head;
   
    while(true){
        if(fast == NULL || fast->next == NULL)return NULL;
        fast =fast->next->next;
        slow = slow->next;
        if(fast == slow)break;
    }
    fast = head;
    while(fast != slow){
        fast = fast->next;
        slow = slow->next;
    }

    return fast;

}