LeetCode 刷题【141. 环形链表】

141. 环形链表

自己做

解：快慢指针

/*** 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) {ListNode p = head;ListNode q = head;while(p != null){//p为快指针，走两步p = p.next;if(p != null)                   //防止越界p = p.next;//快指针追上慢指针，说明有环if(p == q)return true;q = q.next;}return false;}
}