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