LeetCode Linked List Cycle (java)
Tags: Algorithm, LeetCode, linked listGiven a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?
Java Solution
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/** * 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 fastP = head.next; ListNode slowP = head; while(fastP != null && fastP != slowP) { if(fastP.next == null) return false; fastP = fastP.next.next; slowP = slowP.next; } return fastP == slowP; } } |
