cswork / libraryOpen practice workspace

Interview guides · PM AM

PM AM Software Engineer Interview Guide

PM AM Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

The Software Engineer role at PM AM is a pivotal position focused on delivering robust, scalable, and efficient software solutions within a high-paced development environment. As a key member of the technical team, you will be responsible for translating business requirements into high-quality code, primarily utilizing the.NET stack. Your work directly influences the functionality and reliability of the products that PM AM provides to its clients. This position demands a blend of deep technical expertise and an appreciation for structured development processes like Agile. You will be expected to navigate complex technical challenges, from database optimization to API integration, while collaborating with cross-functional teams to ensure project success.

This guide is scoped to a Software Engineer candidate at PM AM.

Focus areas

  • .NET Development
  • ASP.NET (Web Framework)
  • Agile Methodologies

The PM AM interview process

PM AM candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Recruiter Screening

Initial screening conducted by a recruiter to evaluate candidate fit.

What to demonstrate

  • Initial screening conducted by a recruiter to evaluate candidate fit
  • Depth in .NET Development

How to prepare

  • Be able to walk your CV end to end in two minutes, and say why this company specifically.
  • Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Assessment

Candidates undergo a technical assessment or aptitude test to evaluate their skills.

What to demonstrate

  • Candidates undergo a technical assessment or aptitude test to evaluate their skills
  • Depth in .NET Development

How to prepare

  • Answer aloud and timed: How does Garbage Collection function in the.NET environment?
  • Answer aloud and timed: What is LINQ and how do you leverage it in your development work?

Technical Interviews

Face-to-face or virtual interviews with technical leads to assess technical knowledge and experience.

What to demonstrate

  • Face-to-face or virtual interviews with technical leads to assess technical knowledge and experience
  • Depth in .NET Development

How to prepare

  • Answer aloud and timed: Can you explain your experience with Web API, Bootstrap, and SQL Server?
  • Answer aloud and timed: Describe the most difficult scenario you faced while doing.NET development and how you resolved it.

Management Interviews

Interviews with management to evaluate professional fit and alignment with company values.

What to demonstrate

  • Interviews with management to evaluate professional fit and alignment with company values
  • Depth in .NET Development

How to prepare

  • Answer aloud and timed: How do you approach the optimization of database queries or the use of cursors in SQL Server?
  • Answer aloud and timed: How do you handle debugging when faced with complex MVC architecture issues?

Where candidates lose points

Structure your answers

Use the STAR method (Situation, Task, Action, Result) when answering behavioral questions to keep your responses concise and impactful.

Know your resume

Be prepared to dive deep into any project you have listed. If it is on your resume, it is fair game for the interviewer.

Be ready to discuss the 'why'

When discussing technical choices, explain why you chose a specific tool or approach over an alternative.

Ask insightful questions

Use the final part of your interview to ask about the team’s current technical challenges or how they manage work-life balance.

Questions & practice

How does Garbage Collection function in the.NET environment?

Medium · Technical & Domain Expertise

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

Describe the most difficult scenario you faced while doing.NET development and how you resolved it.

Medium · Development Scenarios & Problem Solving

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Collapse a redelivered event batch into per-aggregate high-water marks

Easy · hashing · at-least-once · aggregation

You drain a batch of up to 5,000,000 events, each (aggregate_id BIGINT, aggregate_version INT, event_type, payload). The log guarantees order within one aggregate only; the batch merges 64 partitions, and a relay failover has redelivered a range, so an older version for an aggregate can appear after a newer one. Given a map of last_applied_version per aggregate, produce the events worth applying, at most one per (aggregate_id, version), plus the count discarded. Target O(n) time. State the memory for 2,000,000 distinct aggregates and what you do when it does not fit.

Approach

  1. One pass, one hash map from aggregate_id to the highest version kept, and a discard counter. An event whose version is at or below last_applied_version for its aggregate is dropped without further work, which is the whole reason the event carries its version rather than a delta. O(n) expected time, O(d) space in distinct aggregates.
  2. Keep the maximum, never the last occurrence. The redelivered range means the final appearance of an aggregate in the batch can be an older version than one seen earlier in the same batch, so last-wins applies stale state over newer state and the projection regresses with no error anywhere.
  3. Cost the memory instead of calling it large: an 8-byte key plus a 4-byte version is 12 bytes of payload, and an open-addressed table held at a 0.7 load factor costs roughly 17 bytes per entry before per-slot metadata, so 2,000,000 aggregates is tens of megabytes in a native layout and several times that in a runtime that boxes both key and value.
  4. If the distinct set exceeds memory, partition on hash(aggregate_id) mod P and reduce each partition independently. Every event for one aggregate hashes to the same partition, so the per-partition result is exact and the merge is concatenation rather than a second reduction.

Follow-up

  • The payload is a patch rather than a snapshot, so applying only the highest version loses the intermediate changes. What changes in your reduction?
  • How do you detect that version 7 arrived while version 6 was never delivered, and what should the consumer do about the gap?

How do you approach the optimization of database queries or the use of cursors in SQL Server?

Medium · Development Scenarios & Problem Solving

Approach

  1. Name the grain you start from and join outward from it.
  2. Check whether any join is one-to-many before aggregating, or the sums inflate.
  3. Say which index the query would use, and what makes it unusable.
  4. Handle the rows that do not match: that is usually the actual question.

Follow-up

  • How does the query change if that join becomes one-to-many?
  • What happens to this when the table is ten times larger?

Stop tag and share joins from fanning out a page

Medium · join fan-out · semi-joins · many-to-many

resource_tag is (resource_id, tag_id) with PK (resource_id, tag_id); resource_share is (resource_id, shared_with_user_id, permission). The tagged-and-shared listing inner-joins resource to both, filters tenant_id, tag_id = ANY($2) and shared_with_user_id = $3, orders by updated_at DESC and takes 50. Pages come back with fewer than 50 distinct resources and the total in the header is far too high. Explain the row multiplication, rewrite both the page query and the count query so each is correct, and name the index each one needs. PostgreSQL 16.

Approach

  1. Do the arithmetic against the predicates that are actually there. An inner join emits one row per matching child row, and both joins are filtered: tag_id = ANY($2) admits only the requested tags, shared_with_user_id = $3 admits one user's share rows. So a resource holding three of the requested tags and shared with $3 once yields three rows, not one — the multiplier is its count of matching tags times its share rows for that single user, and that second factor is 1 unless the table admits duplicate (resource_id, shared_with_user_id) pairs. LIMIT 50 then limits rows rather than resources, and COUNT(*) counts pairs — the header is the product, not the population.
  2. Reject DISTINCT as the fix. It deduplicates after the product has been built, so the planner must materialise and sort the fanned-out set before the LIMIT can apply, and it leaves any SUM or AVG in the same select list wrong.
  3. Rewrite both filters as semi-joins, keeping resource as the only row source: AND EXISTS (SELECT 1 FROM resource_tag rt WHERE rt.resource_id = r.resource_id AND rt.tag_id = ANY($2)) and the same shape against resource_share. A semi-join stops at the first match per resource and preserves the driving index order, so ORDER BY updated_at DESC, resource_id DESC LIMIT 50 still stops after 50 rows.
  4. Count with the same predicates and no join at all: SELECT count(*) FROM resource r WHERE r.tenant_id = $1 AND r.status = 'active' AND EXISTS (...) AND EXISTS (...). Nothing multiplies a resource, so the number is the population.

Follow-up

  • The filter changes from 'any of these tags' to 'all of these tags'. Rewrite it and state what it costs relative to the ANY form.
  • A resource can be shared with the same user twice under different permissions. Does your count change, and should it?

What are the primary differences between connected and disconnected architectures in ADO.NET?

Medium · Technical & Domain Expertise

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Can you explain the difference between managed and unmanaged code?

Medium · Technical & Domain Expertise

Approach

  1. Clarify what is being asked and what a complete answer contains.
  2. State your assumptions explicitly before working the problem.
  3. Say what you would check first and why it is the highest-information step.
  4. Work from the requirement backwards to the design.

Follow-up

  • What assumption would you test first?
  • How would you know your answer was wrong?

What is LINQ and how do you leverage it in your development work?

Medium · Technical & Domain Expertise

Approach

  1. Clarify what is being asked and what a complete answer contains.
  2. State your assumptions explicitly before working the problem.
  3. Say what you would check first and why it is the highest-information step.
  4. Work from the requirement backwards to the design.

Follow-up

  • What assumption would you test first?
  • How would you know your answer was wrong?

p99 jumped on one listing filter while p50 stayed flat

Medium · query planning · composite index · percentiles

After a release that added an owner_user_id filter to the resource listing, p99 rose from 90 ms to 1.9 s while p50 stayed at 40 ms. Traffic and row counts are unchanged. resource carries the index (tenant_id, status, updated_at DESC, resource_id DESC). The new query filters tenant_id and owner_user_id, orders by updated_at DESC, resource_id DESC, and takes 20 rows. On PostgreSQL, explain the shape of the regression, prove it from a query plan, and give the index you would add.

Approach

  1. Start from the shape. A flat p50 with a moved p99 means a subset of requests changed cost, not all of them, so the first job is naming the subset. Bucket the endpoint's latency by the tenant's row count; the natural hypothesis is that large tenants are a small share of requests and all of the tail.
  2. Get the plan for the new query on a large tenant with EXPLAIN (ANALYZE, BUFFERS). Expect an index scan over the tenant's range, a filter discarding most of it, then a Sort feeding the Limit, possibly reporting Sort Method: external merge Disk. Read actual rows on the scan node, not estimated.
  3. Explain why the existing index cannot serve it. A composite B-tree is seekable only as a left prefix, and with no equality predicate on status the scan cannot treat updated_at as an ordering, because rows in the tenant's range are ordered by status first. Everything matching must be read and sorted before LIMIT 20 can apply, so a tenant with 400,000 rows pays 400,000 rows to return 20.
  4. Add (tenant_id, owner_user_id, updated_at DESC, resource_id DESC). Equality on the first two columns leaves the index ordered by updated_at within that pair, so the plan becomes an index scan that stops after 20 rows with no Sort node. PostgreSQL can scan a B-tree backwards, so the DESC markers matter only if the two sort columns ever disagree in direction; keeping them explicit documents the order the keyset cursor depends on.

Follow-up

  • The endpoint paginates with OFFSET. What does page 500 cost with your index, and what does the keyset version cost?
  • How would you have caught this before release, given that a 10,000-row seed database produces the same plan shape at an unnoticeable cost?

Suggested practice checklist

Built from the rounds and topics PM AM candidates report.

Day 1 — Map the PM AM loop

  • Write out the reported sequence: Recruiter Screening, Technical Assessment, Technical Interviews, Management Interviews.
  • For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 4 reported rounds, with the weakest marked.

Day 2 — Work .NET Development

  • Spend the session on .NET Development, which PM AM candidates report being tested on.
  • Write one worked example in .NET Development and time yourself on it.

Deliverable: One timed worked example in .NET Development.

Day 3 — Work ASP.NET (Web Framework)

  • Spend the session on ASP.NET (Web Framework), which PM AM candidates report being tested on.
  • Write one worked example in ASP.NET (Web Framework) and time yourself on it.

Deliverable: One timed worked example in ASP.NET (Web Framework).

Day 4 — Work Agile Methodologies

  • Spend the session on Agile Methodologies, which PM AM candidates report being tested on.
  • Write one worked example in Agile Methodologies and time yourself on it.

Deliverable: One timed worked example in Agile Methodologies.

Day 5 — Answer out loud: Technical & Domain Expertise

  • Answer aloud, timed: What are the primary differences between connected and disconnected architectures in ADO.NET?
  • Answer aloud, timed: Can you explain the difference between managed and unmanaged code?

Deliverable: Spoken answers to 2 reported Technical & Domain Expertise question(s), under time.

Day 6 — Answer out loud: Development Scenarios & Problem Solving

  • Answer aloud, timed: Describe the most difficult scenario you faced while doing.NET development and how you resolved it.
  • Answer aloud, timed: How do you approach the optimization of database queries or the use of cursors in SQL Server?

Deliverable: Spoken answers to 2 reported Development Scenarios & Problem Solving question(s), under time.

Day 7 — Answer out loud: Process & Behavioral

  • Answer aloud, timed: How have you utilized Agile methodologies in your previous roles to manage project timelines?
  • Answer aloud, timed: Why are you interested in joining a company of this size and scope?

Deliverable: Spoken answers to 2 reported Process & Behavioral question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Can you explain your experience with Web API, Bootstrap, and SQL Server?

Medium · Technical & Domain Expertise

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How do you handle debugging when faced with complex MVC architecture issues?

Medium · Development Scenarios & Problem Solving

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How have you utilized Agile methodologies in your previous roles to manage project timelines?

Medium · Process & Behavioral

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Why are you interested in joining a company of this size and scope?

Medium · Process & Behavioral

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How do you handle shifting requirements or ambiguous project instructions?

Medium · Process & Behavioral

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?