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;
* };
*/
/**
* 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
*
*
* @param pHead ListNode类
* @return ListNode类
*/
struct ListNode* EntryNodeOfLoop(struct ListNode* pHead ) {
// write code here
//if(pHead==NULL)
// return NULL;
struct ListNode* fast=pHead;
struct ListNode* slow=pHead;
while(fast){
slow=slow->next;
if(fast->next==NULL)
return NULL;
fast=fast->next->next;
if(fast==slow){
fast=pHead;
while(fast!=slow){
fast=fast->next;
slow=slow->next;
}
return fast;
}
}
return NULL;
}