每天一道leetcode141-环形链表 分类:链表 中文链接: https://leetcode-cn.com/problems/linked-list-cycle/description/ 英文链接 https://leetcode.com/problems/linked-list-cycle/description/
给定一个链表,判断链表中是否有环。 进阶: 你能否不使用额外空间解决此题?
思路
代码
/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public boolean hasCycle(ListNode head) {
if(head == null || head.next == null)
return false;
ListNode fast = head.next;
ListNode slow = head;
while(slow != null && fast != null)
{
if(fast == slow)
return true;
slow = slow.next;
if(fast.next != null)
fast = fast.next.next;
else
return false;
}
return false;
}
}
代码讲解