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`