LeetCode 876:链表的中间节点

题目：

代码示例：

package com.zy.leetcode.LeetCode_876;

/**
 * @Author: zy
 * @Date: 2024-12-27-15:41
 * @Description:链表的中间节点
 */
public class ListNode {

    private int val;

    private ListNode next;

    public ListNode(int val, ListNode next) {
        this.val = val;
        this.next = next;
    }

    public ListNode() {
    }

    public ListNode(int val) {
        this.val = val;
    }

    // 链表打印
    private void print(ListNode node) {
        while (node != null) {
            System.out.print(node.val + " -> ");
            node = node.next;
        }
    }

    /**
     * 找链表的中点
     *
     * @param head 头节点
     * @param
     */
    public static ListNode middleNode(ListNode head) {
        ListNode slow = head, fast = head;

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

    /**
     * 数组初始化链表
     */
    public static ListNode initListNode(int[] arr) {
        ListNode dummy = new ListNode(0);
        ListNode cur = dummy;
        for (int num : arr) {
            cur.next = new ListNode(num);
            cur = cur.next;
        }
        return dummy.next;
    }

    /**
     * 获取链表的投节点并返回值
     */
    private static int getHeadVal(ListNode node) {
        if (node != null) {
            return node.val;
        }
        return -1;
    }

    public static void main(String[] args) {

        int[] arr = {1, 2, 3, 4, 5, 6};
        ListNode head = initListNode(arr);
        ListNode listNode = middleNode(head);
        listNode.print(listNode); // 3 -> 4 -> 5 -> null

        //System.out.println("----------------");
        //int headVal = getHeadVal(listNode);
        //System.out.println("HeadVal:" + headVal);

    }

}