Odd Even Linked List

Given the head of a singly linked list, group all odd-indexed nodes together followed by the even-indexed nodes (1-based, first node is odd), preserving relative order within each group, and return the reordered list. This is the LeetCode 328 family, solvable in one pass with O(n) time and O(1) space by splicing the odd and even chains. Odd Even Linked List Given the head of a singly linked list, group all odd-indexed nodes together followed by the even-indexed nodes (1-based, first node is odd), preserving relative order within each group, and return the reordered list. This is the LeetCode 328 family, solvable in one pass with O(n) time and O(1) space by splicing the odd and even chains. SWE MLE linked-list two-pointer medium Frequency Single report Last asked 2026-02-14 Stage onsite-coding Odd Even Linked List Given the head of a singly linked list, group all nodes at odd indices together followed by the nodes at even indices, and return the reordered list. The first node is considered odd, the second node is even, and so on. Preserve the relative order within both groups. Examples 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