Binary Tree Right Side View

Binary Tree Right Side View is LeetCode problem #199, frequently asked in Meta (Facebook) interviews with tags Tree, BFS, DFS, and Binary Tree.[1][8]

Problem Statement

Given the root of a binary tree, imagine you are standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.[2][7][8][1]

Example Inputs/Outputs

Example 1: Input: root = [1,2,3,null,5,null,4] Output: [1,3,4] Explanation: From the right side, nodes 1, 3, and 4 are visible.[5][2]

Example 2: Input: root = [1,null,3] Output: [1,3] Explanation: Nodes 1 and 3 form the right side view.[5]

Example 3: Input: root = [] Output: [] Explanation: Empty tree returns empty list.[5]

Constraints

• Number of nodes in the tree is in the range .
• -100 <= Node.val <= 100[8][5]