package org.example;

public class ReverseList {

public static ListNode reverseList(ListNode head) {

// input check, null

if (head == null) {

return null;

}

// from left to right

ListNode dummy = new ListNode();

dummy.next = null;

ListNode curr = head;

while (curr != null) {

ListNode temp = curr.next;

curr.next = dummy.next;

dummy.next = curr;

curr = temp;

}

return dummy.next;

}

public static void main(String[] args) {

System.out.println("hello,world");

// 初始化链表 1 -> 2 -> 3 -> 4 -> 5

ListNode head = new ListNode(1,

new ListNode(2,

new ListNode(3,

new ListNode(4,

new ListNode(5)))));

head = ReverseList.reverseList(head);

// 遍历链表

ListNode current = head;

while (current != null) {

System.out.print(current.val + " -> ");

current = current.next;

}

}

}