143. Reorder List

Description

Given a singly linked list L: L₀→L₁→…→L_n-1→L_n,

reorder it to: L₀→L_n→L₁→L_n-1→L₂→L_n-2→…

You may not modify the values in the list's nodes, only nodes itself may be changed.

Example 1:

Given 1->2->3->4, reorder it to 1->4->2->3.

Example 2:

Given 1->2->3->4->5, reorder it to 1->5->2->4->3.