package main

import "fmt"

type Node[T any] struct {
	Next  *Node[T]
	Value T
}

type LinkedList[T any] struct {
	Head *Node[T]
}

func NewLinkedList[T any]() *LinkedList[T] {
	return &LinkedList[T]{}
}

func (ll *LinkedList[T]) addNode(value T) {
	n := Node[T]{Next: ll.Head, Value: value}
	ll.Head = &n
}

func (ll *LinkedList[T]) String() string {
	s := " <- head"
	for element := ll.Head; element != nil; element = element.Next {
		s = fmt.Sprintf("%v %s", element.Value, s)
	}
	return s
}

func (ll *LinkedList[T]) Reverse() {
	cn := ll.Head
	var next, prev *Node[T]

	for cn != nil {
		next = cn.Next
		cn.Next = prev
		prev = cn
		cn = next
	}
	ll.Head = prev
}

func main() {
	ll := NewLinkedList[int]()
	ll.addNode(1)
	ll.addNode(2)
	ll.addNode(3)
	ll.addNode(4)
	ll.addNode(5)
	fmt.Println(ll)
	ll.Reverse()
	fmt.Println(ll)
}