rotation on Binary Tree

Last updated: April 12, 2026

Quick Overview

Perform a rotation on a binary tree and return the result.

Grubhub

Coding & Algorithms

Software Engineer

Grubhub

April 12, 2026

Software Engineer

Onsite

Coding & Algorithms

Easy

2,887 solved

Perform a rotation on a binary tree and return the result.

This coding problem is frequently asked during Onsite at Grubhub. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Grubhub expects candidates to write production-quality code, not just solve the puzzle.

What the Interviewer Expects

Identify the correct data structure and algorithm for the problem
Write clean, bug-free code with proper variable naming
Analyze time and space complexity correctly
Handle basic edge cases (empty input, single element)
Communicate your thought process while coding

Key Topics to Cover

Edge cases and input validation

Common algorithm patterns (sliding window, two pointers, BFS/DFS)

Tree structures and recursion

Graph algorithms and traversal

Binary search and divide and conquer

How to Approach This

Clarify input constraints and edge cases before writing code.
Walk through your approach verbally and confirm with the interviewer before coding.
Start with a brute force solution, then optimize. Mention time and space complexity.
Test your solution with examples, including edge cases like empty input or duplicates.
Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.

Possible Follow-up Questions

What is the worst-case input for your solution?
How would your solution change if the input was sorted?
Can you optimize the space complexity of your solution?
How would you modify your solution to handle streaming input?

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Practice DSA Problems

Sample Answer

Problem Analysis

To perform a rotation on a binary tree, we need to identify the type of rotation. A common rotation is a right or left rotation, which can be viewed as a restructuring of the tree to maintain the bina...

Approach

Identify Rotation Node: Assume we are given a node x where the rotation will be performed.
Perform Right Rotation:
- Set newRoot to x.left.
- Set x.left to `newRoot.righ...

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Grubhub Software Engineer Interview Guide

Interview process, tips, and preparation timeline