Prep chat gpt za la n do - sulabh84/IntPrep GitHub Wiki

Here’s what I found regarding programming questions and interview structure for a Senior Java Developer (sometimes referred to as “Zalando Lounge”) at Zalando:

Interview Overview

1. Coding/Screening (often via Codility or live coding)

  • Many candidates begin with a Codility test—typically 2–3 algorithmic problems; the difficulty ranges from easy to medium. 120 minutes is a common time frame Glassdoor+2Glassdoor+2Reddit+1.

  • In live coding rounds, candidates face LeetCode-style algorithm problems, including graph and sorting tasks GlassdoorReddit+2Reddit+2.

  • Some Reddit feedback details:

    “They give you a screening test. It contains 3 problems … third is a genuine LC medium.” Reddit
    “One question was past project related, one was Java related and one leetcode medium.” Reddit

2. Technical Rounds (General Tech & System Design)

3. Behavioral / HR Rounds

  • Typically include questions about past experiences, project contributions, motivation, conflict resolution, and future goals Code DailyRedditclevercoder.net.

  • Many candidates report this as a final, often informal round focusing on fit and logistics rather than new technical problems RedditGlassdoor.

Common Programming Question Categories

From various candidate reports and shared resources:

Algorithms & Data Structures

  • Palindromic number checking without converting to string

  • Path simplifier (similar to Unix path canonicalization)

  • Count bits set in the result of A * B

  • Find maximal matches by “hammering down” N sorted values—matching problem

  • Return largest even sum of K elements from an array

  • String compression by character frequency (e.g., “aaabb” ⇒ “a3b2”)

  • Partition index in an array (elements to left are smaller than right)

  • Subsequence maximum sum (DP)

  • Misc: Tic-tac-toe design, postfix evaluation, tree subtree identification, sorting by timestamps Code Daily.

Java, OOP & System Concepts

  • Implementations of Singleton, immutability, generics, thread-safety (e.g., synchronized counters)

  • Understanding HashMap complexity and internals

  • Decorator pattern, dependency injection types, circuit breaker and retry strategies

  • API idempotency, REST vs. PATCH, security in microservices

  • Differences between NoSQL and SQL, ACID properties, scalability of DBs Code DailyGlassdoor+1Glassdoor Australia.

System Design / Architecture

  • Examples include designing shopping baskets, ticket booking systems, cargo delivery flows

  • Emphasis on microservices vs. monolith, event sourcing, high-load stock update APIs

  • Scaling backend components like Redis/Postgres, defining SLOs and RFC processes Code DailyGlassdoorGlassdoor Australiastatic.glassdoor.de.

Candidate Insights (via Reddit)

  • One describes the interview phases:

    1. Screening test with 3 problems

    2. Recruiter call on salary

    3. Live coding + theoretical (REST, Docker)

    4. System design + technical discussion Reddit

  • Another experience:

    “Coding: URL … System design was quite general … you design cargo delivery system” Reddit

  • Others note a pattern:

    “Round 1 is cultural fit. Round 2 will be 2x LC Mediums. Round 3 … design Netflix, Dropbox… Round 4 … tech stack” (Fullstack context) Reddit

Summary Table

Stage | Typical Focus | Example Tasks / Topics -- | -- | -- Codility / Live Coding | Algorithms (medium) | LeetCode-style problems on graphs, sorting, arrays Technical Interview | Java & System Knowledge | OOP, threading, HashMap, REST/Microservices, dependency injection, concurrency System Design Interview | Designing Scalable Systems | Shopping basket, ticket system, cargo delivery, high-load APIs, scaling services Behavioral / HR Round | Fit, soft skills, logistics | Motivation, past projects, teamwork, conflict resolution
Here’s what I found regarding programming questions and interview structure for a Senior Java Developer (sometimes referred to as “Zalando Lounge”) at Zalando: Interview Overview 1. Coding/Screening (often via Codility or live coding) 
Many candidates begin with a Codility test—typically 2–3 algorithmic problems; the difficulty ranges from easy to medium. 120 minutes is a common time frame
[Glassdoor+2Glassdoor+2](https://www.glassdoor.com/Interview/Zalando-Java-Backend-Developer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C30.htm?utm_source=chatgpt.com)
[Reddit+1](https://www.reddit.com/r/cscareerquestionsEU/comments/ikcglu?utm_source=chatgpt.com)
.

In live coding rounds, candidates face LeetCode-style algorithm problems, including graph and sorting tasks
[Glassdoor](https://www.glassdoor.de/Vorstellungsgespr%C3%A4ch/Zalando-Softwareentwickler-Fragen-im-Vorstellungsgespr%C3%A4ch-EI_IE613421.0%2C7_KO8%2C26.htm?utm_source=chatgpt.com)
[Reddit+2Reddit+2](https://www.reddit.com/r/cscareerquestionsEU/comments/185bqq7?utm_source=chatgpt.com)
.

Some Reddit feedback details:

    “They give you a screening test. It contains 3 problems … third is a genuine LC medium.”
    [Reddit](https://www.reddit.com/r/cscareerquestionsEU/comments/seqmtj?utm_source=chatgpt.com)

    “One question was past project related, one was Java related and one leetcode medium.”
    [Reddit](https://www.reddit.com/r/cscareerquestionsEU/comments/txih59?utm_source=chatgpt.com)

  1. Technical Rounds (General Tech & System Design)

    Interviews often include:

     Technical discussions on Java (OOP, microservices, REST, Spring Boot, caching, etc.)
 [Glassdoor](https://www.glassdoor.com/Interview/Zalando-Senior-Software-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C32.htm?utm_source=chatgpt.com)
 [clevercoder.net](https://clevercoder.net/2018/04/14/zalando-how-to-pass-the-interview/?utm_source=chatgpt.com)
 [Code Daily](https://codedaily.in/zalando-interview-questions/?utm_source=chatgpt.com)
 .

 System Design rounds, e.g., designing a shopping basket, ticket booking system, or a cargo delivery service
 [Glassdoor](https://www.glassdoor.com/Interview/Zalando-Senior-Software-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C32.htm?utm_source=chatgpt.com)
 [Glassdoor Australia](https://www.glassdoor.com.au/Interview/Zalando-Senior-Backend-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C31.htm?utm_source=chatgpt.com)
 [Code Daily](https://codedaily.in/zalando-interview-questions/?utm_source=chatgpt.com)
 [Glassdoor](https://www.glassdoor.de/Vorstellungsgespr%C3%A4ch/Zalando-Softwareentwickler-Fragen-im-Vorstellungsgespr%C3%A4ch-EI_IE613421.0%2C7_KO8%2C26.htm?utm_source=chatgpt.com)
 .

 Backend technology deep dives, such as scaling Redis/Postgres, HTTP/HTTP2 differences, SLOs, RFC processes
 [Glassdoor Australia](https://www.glassdoor.com.au/Interview/Zalando-Senior-Backend-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C31.htm?utm_source=chatgpt.com)
 [static.glassdoor.de](https://static.glassdoor.de/Vorstellungsgespr%C3%A4ch/Zalando-Senior-Backend-Engineer-Fragen-im-Vorstellungsgespr%C3%A4ch-EI_IE613421.0%2C7_KO8%2C31.htm?utm_source=chatgpt.com)
 .

  2. Behavioral / HR Rounds

    Typically include questions about past experiences, project contributions, motivation, conflict resolution, and future goals Code Daily Reddit clevercoder.net .

    Many candidates report this as a final, often informal round focusing on fit and logistics rather than new technical problems Reddit Glassdoor .

Common Programming Question Categories

From various candidate reports and shared resources: Algorithms & Data Structures

Palindromic number checking without converting to string

Path simplifier (similar to Unix path canonicalization)

Count bits set in the result of A * B

Find maximal matches by “hammering down” N sorted values—matching problem

Return largest even sum of K elements from an array

String compression by character frequency (e.g., “aaabb” ⇒ “a3b2”)

Partition index in an array (elements to left are smaller than right)

Subsequence maximum sum (DP)

Misc: Tic-tac-toe design, postfix evaluation, tree subtree identification, sorting by timestamps
[Code Daily](https://codedaily.in/zalando-interview-questions/?utm_source=chatgpt.com)
.

Java, OOP & System Concepts

Implementations of Singleton, immutability, generics, thread-safety (e.g., synchronized counters)

Understanding HashMap complexity and internals

Decorator pattern, dependency injection types, circuit breaker and retry strategies

API idempotency, REST vs. PATCH, security in microservices

Differences between NoSQL and SQL, ACID properties, scalability of DBs
[Code Daily](https://codedaily.in/zalando-interview-questions/?utm_source=chatgpt.com)
[Glassdoor+1](https://www.glassdoor.com/Interview/Zalando-Java-Developer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C22.htm?utm_source=chatgpt.com)
[Glassdoor Australia](https://www.glassdoor.com.au/Interview/Zalando-Senior-Backend-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C31.htm?utm_source=chatgpt.com)
.

System Design / Architecture

Examples include designing shopping baskets, ticket booking systems, cargo delivery flows

Emphasis on microservices vs. monolith, event sourcing, high-load stock update APIs

Scaling backend components like Redis/Postgres, defining SLOs and RFC processes
[Code Daily](https://codedaily.in/zalando-interview-questions/?utm_source=chatgpt.com)
[Glassdoor](https://www.glassdoor.com/Interview/Zalando-Senior-Software-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C32.htm?utm_source=chatgpt.com)
[Glassdoor Australia](https://www.glassdoor.com.au/Interview/Zalando-Senior-Backend-Engineer-Interview-Questions-EI_IE613421.0%2C7_KO8%2C31.htm?utm_source=chatgpt.com)
[static.glassdoor.de](https://static.glassdoor.de/Vorstellungsgespr%C3%A4ch/Zalando-Senior-Backend-Engineer-Fragen-im-Vorstellungsgespr%C3%A4ch-EI_IE613421.0%2C7_KO8%2C31.htm?utm_source=chatgpt.com)
.

Candidate Insights (via Reddit)

One describes the interview phases:

    Screening test with 3 problems

    Recruiter call on salary

    Live coding + theoretical (REST, Docker)

    System design + technical discussion
    [Reddit](https://www.reddit.com/r/cscareerquestionsEU/comments/seqmtj?utm_source=chatgpt.com)

Another experience:

    “Coding: URL … System design was quite general … you design cargo delivery system”
    [Reddit](https://www.reddit.com/r/cscareerquestionsEU/comments/185bqq7?utm_source=chatgpt.com)

Others note a pattern:

    “Round 1 is cultural fit. Round 2 will be 2x LC Mediums. Round 3 … design Netflix, Dropbox… Round 4 … tech stack” (Fullstack context)
    [Reddit](https://www.reddit.com/r/cscareerquestionsEU/comments/vgjfee?utm_source=chatgpt.com)

Summary Table Stage Typical Focus Example Tasks / Topics Codility / Live Coding Algorithms (medium) LeetCode-style problems on graphs, sorting, arrays Technical Interview Java & System Knowledge OOP, threading, HashMap, REST/Microservices, dependency injection, concurrency System Design Interview Designing Scalable Systems Shopping basket, ticket system, cargo delivery, high-load APIs, scaling services Behavioral / HR Round Fit, soft skills, logistics Motivation, past projects, teamwork, conflict resolution How to Prepare

Practice algorithm problems: particularly medium difficulty tasks similar to LeetCode (graphs, arrays, sliding window, partition, DP).

Brush up core Java: internal data structures, OOP design patterns, generics, concurrency.

Review system design fundamentals: microservices vs monolith, API design, scalability, eventual consistency.

Be ready to explain past projects and articulate design decisions and personal impact.

Align with involvement in coding tests, technical rounds, and behavioral discussions.

Let me know if you'd like tailored practice problems, mock interview scenarios, or tips for any specific stage!

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