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 ) {
    // write code here
    if(head == NULL || head->next == NULL){
        return false;
    }

    struct ListNode* slow = head;
    struct ListNode* fast = head->next;
    while(fast != NULL && fast->next != NULL){
        slow = slow->next;
        fast = fast->next->next;
        if(slow == fast){
            return true;
        }
    }
    
    return false;
}