Binary Tree Right Side View

Binary Tree Right Side View is a Medium Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Tree Traversal Patterns (DFS & BFS) pattern, in the Level Order Traversal subpattern.

Problem statement

Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

Example 1:

Input: root = [1,2,3,null,5,null,4]

Output: [1,3,4]

Explanation:

Example 2:

Input: root = [1,2,3,4,null,null,null,5]

Output: [1,3,4,5]

Explanation:

Example 3:

Input: root = [1,null,3]

Output: [1,3]

Example 4:

Input: root = []

Output: []

Constraints:

- The number of nodes in the tree is in the range [0, 100].

- -100 <= Node.val <= 100

Topics and companies

Topics: Tree, Depth-First Search, Breadth-First Search, Binary Tree.

Reported in interviews at Facebook, Amazon, ByteDance, Bloomberg, Microsoft.

How to practise Binary Tree Right Side View on Thita.ai

Starter code is provided in C, C#, C++, Go, Java, JavaScript and Python. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(N), where N is the number of nodes in the tree. Each node is visited exactly once during the level order traversal. time and O(W), where W is the maximum width of the tree (maximum number of nodes at any level). In the worst case (complete binary tree), W = N/2, so O(N). space.

Open Binary Tree Right Side View in the code editor, or read the Binary Tree Right Side View editorial for a worked solution with its approach and complexity analysis.

Where Binary Tree Right Side View sits in the DSA pattern sheet

• Tree Traversal Patterns (DFS & BFS) pattern guide
• Level Order Traversal subpattern
• The full DSA patterns sheet
• All coding practice problems

Problems related to Binary Tree Right Side View

Other problems that use the same Level Order Traversal and Tree Traversal Patterns (DFS & BFS) techniques:

• Binary Tree Level Order Traversal — Medium, same subpattern
• Binary Tree Zigzag Level Order Traversal — Medium, same subpattern
• Find Largest Value in Each Tree Row — Medium, same subpattern
• Maximum Level Sum of a Binary Tree — Medium, same subpattern
• All Nodes Distance K in Binary Tree — Medium, same pattern
• Balanced Binary Tree — Easy, same pattern