算法刷题 -- 141. 环形链表 ＜难度 ★☆☆＞

1、力扣原题

https://leetcode-cn.com/problems/linked-list-cycle/

2、解题思路：快慢指针

public class Solution {
    public boolean hasCycle(ListNode head) {
        if (head == null || head.next == null) {
            return false;
        }

        ListNode slow = head;
        ListNode fast = head.next.next;
        while(fast != null && fast.next != null) {
            if (slow == fast) {
                return true;
            }
            slow = slow.next;
            fast = fast.next.next;
        }
        return false;
    }
}