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Answer
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Practice for technical interviews and cloud certifications, one clear question at a time.
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Android is planned first; iOS will follow. Neither app is available to download yet.
Practice question
Two pointers each move only forward through an array, neither pointer moves backward, and every loop iteration advances at least one pointer. Why can a nested while loop still be O(n)?
This Coding Interview example uses one Free practice question. It does not save your progress or schedule reviews.
How Patternly works
Learn from the answer.
Answer, see the reason, then try again with a clearer idea.
02
See why
Read feedback that connects the answer to the idea behind it.
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Try again
Return to the question with a clearer understanding.
Inside the app
A place to return to your practice.
For people preparing for technical interviews or studying cloud and AI concepts. Choose a topic, work through questions and explanations, and revisit your learning history.
Choose a focus
Browse tracks and topics in Practice. Access depends on the topic and mode you select.
Understand the reasoning
Work through practice questions and read feedback. Use explanations to examine the choices, not just memorise an answer.
Return to your work
The app keeps learning history and a Progress view. This website demo does not save progress or schedule reviews.
Actual screens from the iOS development version, using a fictional profile and demonstration practice history. Premium access is enabled locally; no purchase is shown.
Find your focus
What are you preparing for?
Explore nine learning tracks for coding interviews, system design, cloud and AI certifications.
Coding Interview: DSA & Problem Solving
Find an approach to unfamiliar coding problems.
Backend System Design Interview
Design reliable systems and explain your choices.
Object-Oriented Design Interview
Turn requirements into clear, flexible object designs.
Frontend System Design Interview
Plan interfaces that stay fast as they grow.
Google Cloud Associate Cloud Engineer
Practice running and managing Google Cloud services.
Independent study content. Not affiliated with or endorsed by Google.
AWS Certified Solutions Architect - Associate
Choose AWS services for real-world needs.
Independent study content. Not affiliated with or endorsed by Amazon Web Services.
Microsoft Azure Administrator Associate AZ-104
Practice setting up and troubleshooting Azure.
Independent study content. Not affiliated with or endorsed by Microsoft.
Microsoft Azure AI Fundamentals AI-901
Learn AI concepts and when to use Azure AI services.
Independent study content. Not affiliated with or endorsed by Microsoft.
Claude Certified Architect – Professional
Independent practice for designing and operating production Claude systems, from solution architecture and evaluation to governance and delivery.
Independent study content. Not affiliated with or endorsed by Anthropic.
Before you begin
Questions about Patternly
Can I download the app?
Android is planned first; iOS will follow. Neither app is available to download yet.
What can I try here?
Choose the Coding Interview or AWS example, answer one question and read its feedback and key idea. You can reset the example or switch tracks. This is a small sample, not a full course or an assessment of exam readiness.
What is Free, and what requires Premium?
In the current app, Free-eligible Coding Interview and Certification tracks include one complete free topic. The remaining content, all Design Interview modes, certification exam simulations and Coding Interview Mock require Premium access.
Premium is intended to cover Premium content across tracks through one subscription. Purchases are not available yet. The website demo is free and does not sell subscriptions.
Do I need an account?
No account is needed for this demo. In the app, you can begin Free learning as a guest. Premium purchases require an account when they become available.
Who is responsible, and how can I report a problem?
Patternly is operated by Łukasz Kurczab. Its learning material is independent of certification providers. It does not guarantee exam results or replace official exam guidance.
For a question or content issue, include the track and question title, and describe what seems wrong. Do not send passwords or recovery codes.