题解 | #判断链表中是否有环#

#include <stdbool.h>
/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

/**
 * 
 * @param head ListNode类 
 * @return bool布尔型
 */
bool hasCycle(struct ListNode* head ) 
{
    if(head == NULL) return false;
    
    struct ListNode *slow = head;
    struct ListNode *fast = head->next;//经典快慢指针
    while (slow != NULL && fast != NULL && fast->next != NULL) //快慢指针需要考虑快指针的越界问题
    {
       if(slow == fast)
       {
         return true;
       }
       else 
       {
         slow = slow->next;
         fast = fast->next->next;
         continue;
       }
    }
    
    return false; 

}