mediumLinked ListPattern: Mixed
Alternate Node Reordering Solution
Problem Statement
Given a singly linked list, reorder its nodes such that all nodes at even indices appear before nodes at odd indices. The relative order of nodes within the even and odd groups must be preserved.
Examples
Example 1:
Input:1 -> 2 -> 3 -> 4 -> 5
Output:2 -> 4 -> 1 -> 3 -> 5
Explanation: Even-indexed nodes (2, 4) appear before odd-indexed nodes (1, 3, 5)
Example 2:
Input:1 -> 2 -> 3
Output:2 -> 1 -> 3
Explanation: Even-indexed node (2) appears before odd-indexed nodes (1, 3)
Constraints
- You may not modify the original linked list
- You must return the reordered linked list
Time: O(n) Space: O(1)
Use two separate lists to store even-indexed and odd-indexed nodes with a time complexity of O(n) and space complexity of O(n)
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