package main

import "fmt"

type ListNode struct {
	Val  int
	Next *ListNode
}

func reverseList(head *ListNode) *ListNode {
	var pre *ListNode
	cur := head
	for cur != nil {
		tmp := cur.Next //暂存初始方向
		cur.Next = pre  //改变链表方向
		pre = cur       //移动指针
		cur = tmp       //移动指针2
	}
	return pre
}

func main() {
	head := &ListNode{
		Val: 1,
		Next: &ListNode{
			Val: 2,
			Next: &ListNode{
				Val: 3,
				Next: &ListNode{
					Val: 4,
					Next: &ListNode{
						Val:  5,
						Next: nil,
					},
				},
			},
		},
	}
	fmt.Printf("%#v\n", head)
	ret := reverseList(head) //反转之后的头节点
	fmt.Printf("%#v\n", ret)
	for ret != nil {
		fmt.Print(ret.Val, "->")
		ret = ret.Next //指针移动，直到链表的尾部
	}

}