You are given the head of a singly linked-list. The list can be represented as:

`L0 → L1 → … → Ln - 1 → Ln`

*Reorder the list to be on the following form:*

`L0 → Ln → L1 → Ln - 1 → L2 → Ln - 2 → …`

You may not modify the values in the list’s nodes. Only nodes themselves may be changed.

**Example 1:**

`Input: head = [1,2,3,4]`

Output: [1,4,2,3]

**Example 2:**

`Input: head = [1,2,3,4,5]`

Output: [1,5,2,4,3]

**Constraints:**

- The number of nodes in the list is in the range
`[1, 5 * 104]`

. `1 <= Node.val <= 1000`

Solution:

Time complexity: O(N)

Space complexity: O(N)