力扣环形链表 l ll

format_push

于 2025-02-11 09:28:44 发布

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CC 4.0 BY-SA版权

文章标签： leetcode 链表算法

本文链接：https://blog.youkuaiyun.com/format_push/article/details/145564023

public class Solution {
    public boolean hasCycle(ListNode head) {
        ListNode slow = head;
        ListNode fast = head;
        while(fast != null && fast.next != null){
            slow = slow.next;
            fast = fast.next.next;
            if(slow == fast){
                return true;
            }

        }
        return false;
    }
    public ListNode detectCycle(ListNode head) {
        ListNode slow = head;
        ListNode fast = head;
        while(fast != null && fast.next != null){
            slow = slow.next;
            fast = fast.next.next;
            if(slow == fast){
                break;
            }
        }
        if(fast == null || fast.next == null){
            return null;
        }
        fast = head;
        if(fast == slow){
            return fast;
        }
        while(fast != slow){
            fast = fast.next;
            slow = slow.next;
            if(fast == slow){
                return fast;
            }
        }
        return null;
    }
}