Boundary Traversal of a Full Complete Balanced Binary Tree (Variant)

Problem: Boundary Traversal of a Full, Complete, Balanced Binary Tree (Variant) Given the root root of a binary tree. The tree is guaranteed to be: Full: each node has either 0 or 2 children Complete: all levels are full except possibly the last, which is filled left to right Balanced: for every node, left/right subtree heights differ by at most 1 Return the boundary traversal in anti-clockwise order: Root (if non-empty) Left boundary (excluding leaves): starting from root.left, go as-left-as-possible down All leaves from left to right Right boundary (excluding leaves): starting from root.right, go as-right-as-possible down, then add nodes bottom-up Each node must appear at most once in the output. Input Format Level-order representation: Line 1: integer n Line 2: n tokens: integer values or null Input is guaranteed to satisfy the full/complete/balanced constraints. Output Format Print boundary values separated by spaces. Constraints 0 <= n <= 2 * 10^5 Node values are 32-bit integers Example Input: 7 1 2 3 4 5 6 7 Output: 1 2 4 5 6 7 3 Example Input 0 Output