#143
Reorder List
medium · failed · 64.7% accepted · 12,470 likes · top 68%
linked list · two pointers · stack · recursion
Description
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:
L0 → L1 → … → Ln - 1 → Ln
Example 2:
L0 → Ln → L1 → Ln - 1 → L2 → Ln - 2 → …
Example 3:
Input: head = [1,2,3,4]
Output: [1,4,2,3]
Example 4:
Input: head = [1,2,3,4,5]
Output: [1,5,2,4,3]
Solution