Leetcode学习笔记：#876. Middle of the Linked List
Given a non-empty, singly linked list with head node head, return a middle node of linked list.
If there are two middle nodes, return the second middle node.
实现：
public ListNode middleNode(ListNode head){
ListNode slow = head, fast = head;
while(fast != null && fast.next != null){
slow = slow.next;
fast = fast.next.next;
}
return slow;
}
思路：
一个慢指针，一个快指针，快指针移动速度为慢指针两倍。