package leetcode

import (
	"github.com/halfrost/LeetCode-Go/structures"
)

// ListNode define
type ListNode = structures.ListNode

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */

func oddEvenList(head *ListNode) *ListNode {
	oddHead := &ListNode{Val: 0, Next: nil}
	odd := oddHead
	evenHead := &ListNode{Val: 0, Next: nil}
	even := evenHead

	count := 1
	for head != nil {
		if count%2 == 1 {
			odd.Next = head
			odd = odd.Next
		} else {
			even.Next = head
			even = even.Next
		}
		head = head.Next
		count++
	}
	even.Next = nil
	odd.Next = evenHead.Next
	return oddHead.Next
}