Acro Service · Software Engineer
Updated · 2026-10-02

Acro Service Software Engineer
Interview Guide

THE 60-SECOND BRIEF

Candidate reports describe Acro Service as a business that delivers services to clients and keeps internal technical operations running. They do not name a specific product line. A Software Engineer there is described as designing, building and maintaining software systems that turn client requirements into working solutions, on internal tools or client-facing applications, alongside the sales and operations teams.

This guide is for candidates interviewing for the Software Engineer role at Acro Service. It covers the three reported rounds, the nine reported questions (SQL joins, search, C versus Java, OOP, database indexing, ambiguity, explaining technical ideas, salary expectations and prioritization), and a seven-day plan that builds toward the screening, the technical assessments and the managerial interviews in order.

Candidates report three rounds over about 3-5 weeks: an Initial Screening, Technical Assessments that include aptitude and pseudocode tests, and Managerial Interviews on leadership and behavior.

SQL (Structured Query Language)SQL JOINsTechnical Interviewing

30 min read

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See the practice prompts

13Practice promptsAcross five skill areas

Candidates describe the Software Engineer role as day-to-day development and maintenance of software: building features with other engineers, troubleshooting existing systems with operations staff, reviewing code and taking part in the full software development lifecycle. Part of the job is translating what sales and management ask for into technical specifications, so the loop tests two things side by side: whether your fundamentals hold up, and whether you can talk about them with people outside engineering.

The technical content candidates report is deliberately basic and broad: the types of SQL joins, how to use indexes to speed up queries, how to implement a search that cuts retrieval time, how C and Java differ in memory management and syntax, and the core principles of Object-Oriented Programming. The requirements candidates list are Java or C, solid SQL and OOP, with agile experience and full-stack tooling as extras. Because the technical stage is reported to include aptitude and pseudocode tests, practise writing logic in clear structured steps rather than depending on one language's syntax, and practise logical and quantitative reasoning, which candidates say people overlook.

The behavioral questions candidates report are practical rather than abstract: how you handle requirements that are not clearly defined, a time you explained a technical concept to a non-technical stakeholder, how you prioritize several deadlines, and what your salary expectations are and how you reached them. One reported question that sits among the behavioral ones, how you handle database indexing to improve query performance, is really a technical question asked in a how-do-you form, so answer it with a method and a short example from your own work.

Preparation therefore splits cleanly. Spend the early days on SQL, indexing, search and sorting, C versus Java and OOP, with every answer backed by a small example you can write out. Spend the later days on four or five stories told in the first person, each with your decision, the trade-off and the result, plus a salary answer built on research. The plan at the end of this guide follows that order.

01

Initial Screening

reported

Candidates report that the Initial Screening gauges your background and your salary expectations, and that an academic record (often cited as 75% or higher in relevant coursework) is reviewed at this point. Treat it as a structured conversation about your CV: be ready to connect your experience to the listed must-haves (Java or C, SQL, OOP), to describe what you personally built, and to state a salary expectation you can justify.

What to demonstrate

  • How your background maps to the Software Engineer requirements: Java or C, SQL and OOP
  • Your salary expectations and the reasoning behind them
  • How precisely you can describe your own contribution to past projects

How to prepare

  • Rewrite each CV project as one sentence on what you built, one on your specific part, and one on a measurable result.
  • Build a salary range from public postings and salary surveys for your level and location, and rehearse the answer to the reported salary-expectations question.
  • Prepare questions for the recruiter on role scope, benefits and working arrangement, and plan to ask for the answers in writing, as the reported tip suggests.
Acro Service Software Engineer candidate reports ↗
02

Technical Assessments

reported

Candidates describe Technical Assessments that include aptitude and pseudocode tests, and describe the technical evaluation overall as multiple-choice assessments plus live coding. The areas they name are search and sorting algorithms, SQL joins and indexing, and Java or C fundamentals. Prepare two separate skills: quick logical and quantitative reasoning for the aptitude part, and writing correct logic in structured steps for the pseudocode part.

What to demonstrate

  • Working knowledge of data structures and algorithms, especially search and sorting
  • SQL joins and indexing applied to practical query problems
  • Java or C fundamentals, including the reported C versus Java comparison on memory management
  • Ability to express a solution as clear pseudocode or functional code

How to prepare

  • Write pseudocode for linear search, binary search and a hash-based lookup, then trace each on a small input including an empty list and duplicates.
  • Draw two small tables with one unmatched row on each side and write out the result of every join type, then explain how you would speed up the slow query that joins them using an index.
  • Make a two-column comparison of C and Java covering manual allocation versus garbage collection, pointers versus references, and where each language's memory errors come from.
  • Explain the four OOP principles with one Java example each, and do a set of logical and quantitative reasoning questions to warm up for the aptitude test.
Acro Service Software Engineer candidate reports ↗
03

Managerial Interviews

reported

The Managerial Interviews are reported to focus on leadership and behavioral aspects. The topics candidates connect to this work are conflict resolution within a team, handling unclear requirements, and professional, respectful communication. Since the role is described as a bridge between engineering and sales or operations, expect to discuss how you work with non-engineers and how you handle competing demands.

What to demonstrate

  • How you handle disagreements and unclear requirements when working with a team
  • How clearly you communicate technical ideas to people outside engineering
  • How you manage competing deadlines and take ownership of decisions

How to prepare

  • Write four stories in situation, decision, result form: unclear requirements, a technical idea explained to a non-technical person, juggling deadlines, and a disagreement with a colleague.
  • Say each story out loud with I, not we, and name the one decision that was yours.
  • Prepare a short answer on how you would review someone's code or document a feature, since code review and documentation are listed as part of the work.
Acro Service Software Engineer candidate reports ↗

PracHub editorial advice for the preparation topics above.

01

Treating the pseudocode test as a syntax test and writing half-correct Java, or leaving the logic vague

Write numbered or indented steps with the input, the loop, the condition and the return value, then trace a small example by hand. Check the empty input, a single element and duplicates before you say you are done.

02

Reciting join definitions without showing what the rows look like

Sketch two small tables with one unmatched row on each side and write the output of INNER, LEFT, RIGHT, FULL and CROSS joins. Mention what NULL does and how a filter in WHERE can quietly turn a LEFT JOIN into an inner join.

03

Answering the indexing question with 'add an index on the slow column'

Describe the sequence: read the query plan, index the filter and join columns in the right order, avoid functions on indexed columns, weigh the write cost, and measure before and after.

04

Giving a salary number with no basis, or deflecting the question entirely

Bring a researched range for your level and location, explain the inputs, and ask for scope and benefits to be confirmed in writing.

05

Telling behavioral stories in the plural, with no personal decision and no result

Say I, name the one decision that was yours, state the trade-off, and end with what changed. For the explanation story, include the outcome and not only the analogy you used.

Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.

8 technical prompts0 include a worked solution

How would you implement a search algorithm to optimize retrieval time?

medium
Technical Fundamentals

How would you implement a search algorithm to optimize retrieval time?

Approach
  1. Start from the access pattern: data size, whether it is sorted, how often it changes, and whether lookups are exact-match, range or prefix. That choice drives the structure more than the algorithm name does.
  2. Lay out the options with costs. Linear search is O(n) and needs no preparation. Binary search on a sorted array is O(log n) per lookup but sorting costs O(n log n) and inserts cost O(n). A hash table gives O(1) average exact-match lookups (O(n) worst case under heavy collisions) and no ordering. A balanced BST or B-tree gives O(log n) lookups, inserts and range scans.
  3. Write binary search correctly in pseudocode: lo = 0, hi = n - 1, loop while lo <= hi, mid = lo + (hi - lo) / 2 (avoids int overflow in C and Java), move lo = mid + 1 or hi = mid - 1. State the loop invariant and test empty input, one element, target smaller than all and larger than all elements.
  4. Handle duplicates with a lower-bound variant (half-open range [lo, hi), keep going left on equality) to find the first occurrence. That variant also answers 'insert position' and 'count of x' (upper bound minus lower bound).
  5. Close on the trade-off: for repeated lookups on static data, sort once and binary search, or build a hash map. For prefix or autocomplete lookups, a trie gives O(L) in the key length. On disk or in a database the same idea becomes a B-tree index.
Follow-up
  • How would you search a sorted array that has been rotated at an unknown pivot?
  • When would you pick a sorted array with binary search over a hash map, given that the hash map is O(1)?
  • How would you find the first and last position of a value that appears many times?

What are the primary differences between C and Java in terms of memory management and syntax?

medium
Technical Fundamentals

What are the primary differences between C and Java in terms of memory management and syntax?

Approach
  1. Memory management in C is manual: local variables live on the stack and are freed when the function returns, and heap memory comes from malloc/calloc and must be released with free. Name the failure modes: leaks, double free, use-after-free, dangling pointers (such as returning a pointer to a local variable, which is undefined behaviour) and buffer overflows, since C does no bounds checking.
  2. In Java, objects are created with new on the heap and reclaimed by a garbage collector once they are unreachable. Arrays are bounds-checked (ArrayIndexOutOfBoundsException) and a null dereference throws NullPointerException rather than corrupting memory. Primitives and object references are passed by value, and there is no pointer arithmetic.
  3. Point out that Java can still leak: references kept in a static collection, a cache or a listener list keep objects reachable. Non-memory resources such as files and sockets still need explicit closing, which is what try-with-resources is for.
  4. On syntax and model: C is procedural, built from functions, structs, header files, the preprocessor and explicit pointers, and compiles to native code. Java puts all code inside classes, has exceptions, generics, interfaces and a standard library of collections, and compiles to bytecode that runs on the JVM.
  5. Close with the trade-off: C gives predictable control over layout and timing for systems and embedded work. Java trades some control and GC pauses for memory safety and faster development on business applications.
Follow-up
  • Can a Java program run out of memory even with a garbage collector? Give an example.
  • What happens in C if you free a pointer and then use it, and how would you detect that?
  • Is Java pass-by-reference or pass-by-value? Explain with a method that reassigns its parameter.

Track a rolling failure rate per destination for circuit decisions

easy
sliding windowring buffercircuit breaker

The egress service delivers about 1,500 webhooks per second across roughly 40,000 destinations, each call bounded by a 10 second timeout. Maintain, per destination, the failure rate over the trailing 60 seconds so a caller can ask before dispatch whether the circuit should open. Attempts arrive as (destination_id, finished_at_ms, outcome). Requirement: amortised O(1) per attempt, with total memory bounded by the destination count rather than by traffic. Give the structure, its exact memory, and the rule that stops a destination with three attempts from opening a circuit.

Approach
  1. Name the exact-deque version and then reject it as the default. Holding timestamps and advancing a tail pointer past anything older than now minus 60 seconds is a correct two-pointer window at amortised O(1) per attempt, but its memory tracks in-window traffic, so one destination in a retry storm holds hundreds of thousands of entries while thousands of quiet destinations hold none.
  2. Use a ring of 60 one-second buckets per destination, each bucket a pair of counters for attempts and failures. On an attempt, advance the ring by the elapsed whole seconds, zeroing at most min(elapsed, 60) buckets, then increment the head. That is amortised O(1) with a fixed footprint per destination.
  3. State the footprint: 60 buckets times two 4-byte counters is 480 bytes of payload per destination, so 40,000 destinations is roughly 20 to 25 MB with per-entry overhead, bounded by the catalogue rather than by the rate. The cost is granularity, since the oldest bucket ages out in whole seconds, which is far tighter than the decision needs.
  4. Require a minimum sample before the circuit may open. A destination with three attempts and three failures reads as 100 percent and is not evidence; a floor of roughly 20 attempts in the window makes the ratio meaningful, and below that floor use a run of consecutive failures as the trigger instead.
Follow-up
  • The fleet is 30 instances and each sees roughly a thirtieth of a destination's traffic. Where does the rate actually live, and what does a per-instance answer get wrong?
  • A destination answers in 9.5 seconds and succeeds. It is not failing but it is consuming your per-destination concurrency. What signal should open the circuit here?

The plan moves in the order of the reported loop: screening basics first, then SQL and indexing, search and pseudocode, C versus Java and OOP, then the behavioral and salary answers, and a full dry run on the last day.

Small steps. Visible outcomes.0 / 7 completed
ONE WEEK · YOUR PACE

Prepare, practise & reflect

One practical outcome each day. Spend longer where you need it.

0 / 7 done
01Map the loop and audit your fundamentals
  • Write the three reported rounds (Initial Screening, Technical Assessments, Managerial Interviews) and under each list what candidates report about it.
  • Rate yourself on Java or C, SQL joins, indexing, search and sorting, OOP, and aptitude-style reasoning, and mark the two weakest.
  • Rewrite two CV projects as: what I built, my part, the result.

Deliverable: A one-page loop map with a rated fundamentals checklist and two rewritten project summaries.

02SQL joins, with real rows
  • Create two small tables with one unmatched row on each side and write the output of every join type by hand.
  • Write a query that finds rows with no match (an anti-join) and one that shows the difference between filtering in ON and in WHERE on a LEFT JOIN.
  • Work through PracHub's practice question on stopping tag and share joins from fanning out a page, then explain why the counts inflated.

Deliverable: A one-page join sheet with sample tables, every join's output, the anti-join, and the solved practice query.

Practice prompt ↗Practice prompt ↗
03Indexing and slow queries
  • Write a slow query that filters and sorts, read its plan, and add a composite index with the column order justified.
  • List four ways an index fails to be used and one write-cost trade-off.
  • Work through PracHub's practice question on listing latency that scales with page size, and write down the debugging sequence.

Deliverable: A written indexing answer with a before-and-after plan example, plus the debugging sequence for the practice scenario.

Practice prompt ↗Practice prompt ↗
04Search and sorting in pseudocode
  • Write pseudocode for linear search, binary search and a hash lookup, state each one's time and space cost, and say when the sorted-input requirement rules binary search out.
  • Trace merge sort and quicksort on a short array, noting stability, worst case and extra memory.
  • Work through PracHub's practice question on a rolling failure rate per destination to practise choosing a data structure from the access pattern.

Deliverable: Pseudocode for three search methods with traced examples, a sorting comparison table, and the practice solution.

Practice prompt ↗Practice prompt ↗
05C versus Java, OOP and aptitude warm-up
  • Build a comparison of C and Java on memory allocation, freeing, pointers versus references, and common memory errors in each.
  • Explain encapsulation, abstraction, inheritance and polymorphism with one short Java example each, including when composition is better than inheritance.
  • Do a set of logical and quantitative reasoning questions and note which types slow you down.

Deliverable: A C-versus-Java table, four OOP examples, and a list of the aptitude question types to repeat.

Practice prompt ↗Practice prompt ↗
06Behavioral stories and the salary answer
  • Write stories for unclear requirements, explaining a technical concept to a non-technical person, and juggling several deadlines, each with the decision, trade-off and result.
  • Write a story about a disagreement with a colleague and how it was resolved.
  • Build your salary range from postings and surveys, and write the two-sentence answer you would give a recruiter.

Deliverable: Four stories in first person plus a researched salary answer, each rehearsed aloud once.

Practice prompt ↗Practice prompt ↗Practice prompt ↗Practice prompt ↗
07Dry run in loop order
  • Run a mock screening: CV walk-through, project summaries and the salary answer.
  • Run a mixed technical session: a join question, an indexing explanation, a search algorithm in pseudocode and the C-versus-Java comparison.
  • Run a mock managerial conversation using your four stories, then write the questions you want to ask about scope, benefits and working arrangement.

Deliverable: A completed mock in loop order with notes on weak answers, and a list of questions to ask.

Practice prompt ↗Practice prompt ↗Practice prompt ↗Practice prompt ↗Practice prompt ↗

Expand any day for tasks and deliverables. Your progress is saved on this device.

Candidates report that the Managerial Interviews focus on leadership and behavioral aspects, and the role is described as working with sales and operations as well as engineers. The reported prompts below cover unclear requirements, explaining technical ideas simply, prioritizing deadlines and salary expectations, so prepare stories that show your own decision and its result.

How do you handle database indexing to improve query performance?

medium
Technical Fundamentals

How do you handle database indexing to improve query performance?

Approach
  1. Answer with a method, not a slogan: I start from the slow query, run EXPLAIN (or the database's equivalent) to see whether it reads the whole table, and only then choose an index.
  2. Index the columns the query filters, joins and sorts on. In a composite B-tree index put equality columns first and the range or sort column after, because an index is usable from its leftmost columns: one on (customer_id, created_at) serves customer_id alone or both, not created_at alone.
  3. Check what makes an index unusable: a function or cast on the column such as WHERE LOWER(email) = ..., a leading wildcard in LIKE '%abc', a type mismatch, or a low-selectivity column such as a flag that most rows share.
  4. State the cost: every index slows INSERT, UPDATE and DELETE and takes storage, so I index for the queries that matter, drop duplicate or unused indexes, and use a covering index only for hot read paths.
  5. Close with verification: compare the plan and timing before and after on realistic data volume. If a story is wanted, give the query, what the plan showed, the index I added and the measured change.
Follow-up
  • Why does column order matter in a composite index, and how would you choose it?
  • What is the difference between a clustered and a non-clustered index?
  • When can an index make things worse, or simply never get used?

How do you handle ambiguity when requirements are not clearly defined?

medium
Behavioral and Process-Oriented

How do you handle ambiguity when requirements are not clearly defined?

Approach
  1. Choose a real case where the request was vague, such as a report or export with no definition of done, and where you made the call on how to proceed rather than waiting to be told.
  2. Show the first move: separate what you know from what you do not, write the open questions down, and put them to the person who owns the answer, such as the requester or the sales or operations contact, instead of guessing.
  3. If answers are slow, say how you moved anyway: write your assumptions in a message and ask for a yes or no, then build the smallest slice that is easy to change and show it early.
  4. Finish with the result: what changed once the requirements settled, how much rework you avoided, and how you recorded the decisions so nobody had to ask again.
  5. The mistake that sinks this story is either waiting passively or silently building on a guess; a strong version shows you asked and you kept moving.
Follow-up
  • What did you do when the stakeholder could not answer your questions?
  • Tell me about a time an assumption you made turned out to be wrong.
  • How do you record requirements once they are agreed?

Tell me about a time you had to explain a technical concept to a non-technical stakeholder.

medium
Behavioral and Process-Oriented

Tell me about a time you had to explain a technical concept to a non-technical stakeholder.

Approach
  1. Pick a concept that had a decision attached, such as why a release slipped, why a query slows a customer-facing page, or why a requested change is larger than it sounds, so the story has a consequence.
  2. Name the audience (for example a sales or HR colleague) and the decision they needed to make, and say what you deliberately left out.
  3. Describe the technique concretely: an analogy from their world, one example with real numbers, no acronyms, and then asking them to explain the point back to you.
  4. Give the outcome: the decision they made, the misunderstanding you avoided, and what you would reuse next time. The role is described as working with sales and operations, so this story is directly relevant.
  5. Avoid a story that ends at 'and they understood' with no result, and avoid wording that makes the listener sound slow.
Follow-up
  • How did you know the person actually understood?
  • What would you do if they pushed for something technically unsafe?
  • Explain a database index to a salesperson in three sentences.

What are your primary salary expectations and how do you determine your market value?

medium
Behavioral and Process-Oriented

What are your primary salary expectations and how do you determine your market value?

Approach
  1. Candidates report that the screening covers salary expectations, so prepare a number before any call: gather ranges for Software Engineer roles at your level and location from public postings and salary surveys, and note how your Java, SQL and project experience compares.
  2. Explain how you determine market value in three inputs: comparable postings, your experience and demonstrated impact, and the location and working arrangement. Do not cite figures you cannot source.
  3. Give a range rather than one figure, where the low end is something you would accept, and tie it to scope: 'based on what I have seen for this level, I am looking at X to Y, and I would like to understand the role and the full package'.
  4. Ask for role scope, benefits and any conditions to be confirmed in writing, as the reported tip advises, and do not agree to terms on the call that you have not seen.
  5. The mistakes are 'whatever you think is fair', an inflated number you cannot justify, or treating your current pay as the only anchor.
Follow-up
  • What if their budget is below your range?
  • Would you trade salary for other benefits, and which ones?
  • How does your current pay affect the figure you gave?

How do you prioritize your tasks when managing multiple project deadlines?

medium
Behavioral and Process-Oriented

How do you prioritize your tasks when managing multiple project deadlines?

Approach
  1. Open with a method: list every deadline with its owner, the impact of missing it and the effort left, then order by impact and date and check dependencies, especially work that blocks someone else.
  2. Do the blocking and high-impact items first, and split large items so a usable piece ships early instead of everything arriving late.
  3. Say how you communicate: when two deadlines cannot both be met, go to whoever set them with a trade-off, for example 'I can deliver A on Tuesday, or both if B is reduced', rather than missing one quietly.
  4. Use one concrete story with the number of items, the call you made, what you deliberately let slip and what happened as a result.
  5. The answer that sinks this is 'I work longer hours' or any version with no visible decision and no trade-off.
Follow-up
  • What do you do when two managers each say their task is the top priority?
  • Tell me about a deadline you missed and what you changed afterwards.
  • How do you estimate the effort of a task before you commit to a date?
  • 01

    How do you handle ambiguity when requirements are not clearly defined?

  • 02

    Tell me about a time you had to explain a technical concept to a non-technical stakeholder.

  • 03

    How do you prioritize your tasks when managing multiple project deadlines?

  • 04

    What are your primary salary expectations and how do you determine your market value?

  • 05

    Tell me about a disagreement with a teammate and how you resolved it.

  • 06

    Walk me through a technical decision on one of your projects and why you made it.

PracHub preparation framework ↗
Is there a technical assessment before the technical interviews?

Candidates report that the Technical Assessments stage includes aptitude and pseudocode tests, and they describe the technical evaluation as a mix of multiple-choice assessments and live coding. Prepare for it by practising logical and quantitative reasoning and by writing search, sorting and SQL logic in clear structured steps.

Acro Service Software Engineer candidate reports ↗
How long does the process take?

Candidates report three rounds over about 3-5 weeks, moving from the Initial Screening to Technical Assessments and then Managerial Interviews. A sensible pace is fundamentals first and behavioral stories later, which is how the seven-day plan in this guide is ordered.

Acro Service Software Engineer candidate reports ↗
Is remote work available?

Candidate reports do not settle the working arrangement. Ask during the Initial Screening, and ask for the answer, the role scope and the benefits to be confirmed in writing, which is what the reported tip recommends.

Acro Service Software Engineer candidate reports ↗
What topics does Acro Service test in interviews?

Candidates report SQL and SQL joins, indexing, search and sorting algorithms, general coding, Java or C fundamentals including the C versus Java comparison, and OOP principles. On the behavioral side they report unclear requirements, explaining technical ideas to non-technical colleagues, prioritization and salary expectations.

Acro Service Software Engineer candidate reports ↗
Do I need Java, C, or both?

The requirements candidates list say Java or C, together with strong SQL and OOP. Be fluent in at least one, and be able to compare the two on memory management: manual allocation and pointers in C against garbage collection and references in Java.

PracHub Software Engineer practice ↗
Does my academic record matter?

Candidates report that an academic record, typically 75% or higher in relevant coursework, is reviewed at the Initial Screening. Be ready to talk through your coursework, and if your grades are not your strongest point, lead with specific projects and your contribution to them.

PracHub Software Engineer practice ↗
How should I answer the salary expectations question?

Candidates report salary expectations come up at the Initial Screening. Research ranges for your level and location from public postings and surveys, give a range whose low end you would accept, and say that the scope and benefits matter. Do not agree to terms you have not seen in writing.

PracHub Software Engineer practice ↗
Sources & methodology 3 sources ↗

No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.