1. 对应力扣题目连接

• 删除链表的倒数第N个节点

2. 实现案例代码

• 思路：使用双指针

package com.dn.test.algorithmExercise.day1;

public class RemoveNthFromEnd {
    public static void main(String[] args) {
        RemoveNthFromEnd solution = new RemoveNthFromEnd();

        // 示例链表：[1, 2, 3, 4, 5]
        ListNode head = new ListNode(1);
        head.next = new ListNode(2);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(4);
        head.next.next.next.next = new ListNode(5);

        // 删除倒数第 2 个节点
        ListNode newHead = solution.removeNthFromEnd(head, 2);
        printList(newHead); // 输出：[1, 2, 3, 5]
    }

    /**
     * 删除指定倒数位置的节点
     *
     * @param head
     * @param n
     * @return
     */
    public ListNode removeNthFromEnd(ListNode head, int n) {
        // 创建一个虚拟节点，指向头节点
        ListNode dummy = new ListNode(0);
        dummy.next = head;

        // 初始化快慢指针都指向虚拟节点
        ListNode fast = dummy;
        ListNode slow = dummy;

        // 将快指针向前移动 n 步
        for (int i = 0; i < n; i++) {
            fast = fast.next;
        }

        // 同时移动快慢指针，直到快指针到达末尾
        while (fast.next != null) {
            fast = fast.next;
            slow = slow.next;
        }

        // 修改慢指针的 next 指针，跳过需要删除的节点
        slow.next = slow.next.next;

        // 返回新的头节点
        return dummy.next;
    }

    /**
     * 打印节点信息
     *
     * @param head
     */
    public static void printList(ListNode head) {
        ListNode current = head;
        while (current != null) {
            System.out.print(current.val + " ");
            current = current.next;
        }
        System.out.println();
    }
}

/**
* 节点类
* 
* /
class ListNode {
    int val;
    ListNode next;

    ListNode() {}

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

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