LeetCode: Linked List Cycle 解题报告

 1 package Algorithms.list;
 2 
 3 import Algorithms.algorithm.others.ListNode;
 4 
 5 /**
 6  * Definition for singly-linked list.
 7  * class ListNode {
 8  *     int val;
 9  *     ListNode next;
10  *     ListNode(int x) {
11  *         val = x;
12  *         next = null;
13  *     }
14  * }
15  */
16 public class HasCycle {
17     public boolean hasCycle(ListNode head) {
18         if (head == null) {
19             return false;
20         }
21         
22         ListNode slow = head;
23         ListNode fast = head;
24         
25         while (fast != null && fast.next != null) {
26             slow = slow.next;
27             fast = fast.next.next;
28             if (slow == fast) {
29                 return true;
30             }
31         }
32         
33         return false;
34     }
35 }