LeetCode -- Linked List cycle

Source: Internet
Author: User

LeetCode -- Linked List cycle

Given a linked list, determine if it has a cycle in it.

Follow up:
Can you solve it without using extra space?

Checks whether a ring exists in the linked list.

The classic algorithm uses the speed pointer to take two steps at a time and one step at a time. If there is a ring, they will definitely meet.

Implementation Code:

/*** Definition for singly-linked list. * public class ListNode {* public int val; * public ListNode next; * public ListNode (int x) {* val = x; * next = null; *} */public class Solution {public bool HasCycle (ListNode head) {if (head = null) {return false;} var p = head; var q = head; while (p! = Null & q! = Null & q. next! = Null) {var t = q; p = p. next; q = q. next. next; if (ReferenceEquals (p, q) {return true ;}} return false ;}}

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