Java 【力扣876】链表的中间结点

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode middleNode(ListNode head) {
       ListNode fast=head;
        ListNode low=head;
        while (fast!=null&&fast.next!=null){
            low=low.next;
            fast=fast.next.next;
        }
        return low;
    }
}