876 , 链表的中间节点

https://leetcode.cn/problems/middle-of-the-linked-list/

 

使用快慢指针

lass Solution {
    public ListNode middleNode(ListNode head) {
        // 排除为空情况
        if(head == null){
            return null;
        }
        // 使用快慢指针
        ListNode slow = head;
        ListNode fast = head;

        while(fast != null && fast.next != null){
            slow = slow.next;
            fast = fast.next.next;
        }
        return slow;
    }
}