Medium
Quiz
#328 Odd Even Linked List
APPROACH
Given the head of a singly linked list, rearrange the nodes so all odd-indexed nodes appear before all even-indexed nodes, preserving the original relative order within each group. Index numbering starts at 1 (first node is odd, second is even, etc.).
Achieve this in O(1) extra space and O(n) time.
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]
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What is the optimal approach for this problem?