Reverse Odd Levels of Binary Tree

Problem Overview
The "Reverse Odd Levels of Binary Tree" problem (LeetCode 2415) requires reversing node values at odd-numbered levels (1, 3, 5, etc.) of a perfect binary tree, where the root is at level 0. Only values are swapped within each odd level; the tree structure remains unchanged.[1][7]

Full Problem Statement
Given the root of a perfect binary tree, reverse the node values at each odd level of the tree.

• For example, suppose the node values at level 3 are from left to right. Then it becomes.[2][3][4][7][1]
• A perfect binary tree is one where all interior nodes have two children and all leaf nodes are at the same level.[7][9][1]

Input/Output Examples

| Example | Input Tree (level-order) | Output Tree (level-order) | Explanation | |---------|---------------------------|----------------------------|-------------| | 1 | [2][3][5][8] | [2][5][3][8] | Level 0: [2] unchanged. Level 1: [3][5] → [5][3]. Level 2: [8] unchanged. [5] | | 2 | [7] | [7] | Level 0: [7] unchanged. Level 1: → . [5] |

Constraints

• The number of nodes in the tree is in the range [1, 2¹⁴].
• -10⁹ ≤ Node.val ≤ 10⁹
• The tree is guaranteed to be perfect (all nodes have 0 or 2 children; leaves at same depth).[1][7]