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Top 50 clean code Interview Questions

The most frequently asked clean code questions across all roles and companies, ranked by real interview frequency. Updated daily.

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CodingStart here. 49 questions · ~1208 min
Python Data Cleaning FunctionEasy
Practice

Clean a list of records by trimming strings and removing null or empty fields while preserving record order.

Hash Tablesclean codeArraysXcceleratedAct Digital
Debugging ApproachEasy
Practice

Debug and implement a function that returns the index of the first non-repeating character.

Hash Tablescode analysisStackDorman ProductsZendesk
Ingest Nested JSON to DeltaHard
Practice
Recently asked

Recursively flatten nested JSON logs and group normalized records by a partition field for Delta ingestion.

Codingclean codedata persistenceDatabricks
Live Coding System DesignHard
Practice
Recently asked

Implement a cancellable priority queue using a heap and hash map while preserving correct ordering.

system designclean codesoftware engineeringThe Boston Consulting Group
Prevent Injection via Input SanitizationEasy
Practice
Recently asked

Escape HTML-sensitive characters in untrusted text to prevent markup injection using a single linear scan.

Hash TablesCodingclean codeMicrosoft
Python List Append ClassEasy
Practice

Implement a Python class that encapsulates list creation and appends mixed values through clear methods.

Recursionclean codeLinked ListsDeloitte
Demonstrate Object-Oriented PrinciplesHard
Practice

Build an extensible shape calculator using abstraction, inheritance, encapsulation, and polymorphism.

RecursionHash TablesCodingBristol Myers Squibb
Production-Ready Modular CodeEasy
Practice

Remove duplicate integers while preserving first-occurrence order using an optimized, modular linear-time approach.

Hash Tablesdeduplicationclean codeAndreessen Horowitz
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