141. 環形鏈表

141.環形鏈表

 

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