Odd Even Linked List

Medium

Given the head of a singly linked list, group all the nodes at odd positions together followed by the nodes at even positions (1-indexed), preserving relative order within each group. Return the reordered list.

Example 1

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

Example 2

Input:  head = [2,1,3,5,6,4,7]
Output: [2,3,6,7,1,5,4]

Constraints

• 0 <= number of nodes <= 10^4
• -10^6 <= Node.val <= 10^6