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DEKA Research & Development Software Engineer Interview Guide

DEKA Research & Development Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

At DEKA Research & Development, the Software Engineer role is not merely about writing code; it is about architecting the digital intelligence that powers life-changing medical technologies. You will work within a high-stakes, multidisciplinary environment where software interacts directly with complex electro-mechanical systems. Your contributions will bridge the gap between abstract design and physical reality, ensuring that devices are not only innovative but safe, reliable, and performant for the patients who depend on them. The work is intellectually demanding and highly collaborative. You will engage with mechanical, electrical, and quality engineers to solve problems that exist at the intersection of hardware and software.

This guide is scoped to a Software Engineer candidate at DEKA Research & Development.

Focus areas

  • Object-Oriented Programming (OOP)
  • PID Control
  • Memory Management

The DEKA Research & Development interview process

DEKA Research & Development candidates report 5 rounds over 4-6 weeks. The stages below are what candidates describe, not a published process.

Initial Screening

The process begins with initial screenings to assess candidate fit.

What to demonstrate

  • The process begins with initial screenings to assess candidate fit
  • Depth in Object-Oriented Programming (OOP)

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 Evaluations

Candidates undergo deep-dive technical evaluations with senior engineering staff.

What to demonstrate

  • Candidates undergo deep-dive technical evaluations with senior engineering staff
  • Depth in Object-Oriented Programming (OOP)

How to prepare

  • Answer aloud and timed: Explain your process for debugging a complex issue that spans both hardware and software components.
  • Answer aloud and timed: How do you approach the documentation of software requirements in a regulated environment?

Discussion of Past Projects

Candidates are expected to provide specific examples from past projects.

What to demonstrate

  • Candidates are expected to provide specific examples from past projects
  • Depth in Object-Oriented Programming (OOP)

How to prepare

  • Answer aloud and timed: What experience do you have with version control and continuous integration in a team setting?
  • Answer aloud and timed: These questions test your ability to deconstruct ambiguous, high-pressure problems and arrive at data-driven solutions.

Evidence-Based Assessment

Focus on evidence-based answers, discussing logic, mistakes, and successes.

What to demonstrate

  • Focus on evidence-based answers, discussing logic, mistakes, and successes
  • Depth in Object-Oriented Programming (OOP)

How to prepare

  • Answer aloud and timed: Describe a time you had to diagnose a system failure with limited information; what was your process?
  • Answer aloud and timed: How do you prioritize tasks when faced with conflicting requirements from different engineering disciplines?

Final Evaluation

The process concludes with a final evaluation to determine candidate suitability.

What to demonstrate

  • The process concludes with a final evaluation to determine candidate suitability
  • Depth in Object-Oriented Programming (OOP)

How to prepare

  • Answer aloud and timed: Tell me about a technical trade-off you had to make—how did you justify your decision?
  • Answer aloud and timed: These questions focus on your ability to work within a team, communicate effectively, and maintain the high standards required at DEKA Research & Development.

Where candidates lose points

Own your projects

Be prepared to dive deep into any project you list on your resume. You should be able to explain the "why" behind your technical decisions.

Focus on the "How

When answering questions, focus on your process and your logic rather than just the final result.

Prepare for ambiguity

Engineering often involves unknowns. Show us how you navigate uncertainty and where you go to find answers.

Questions & practice

These questions test your ability to deconstruct ambiguous, high-pressure problems and arrive at data-driven s

Medium · Problem-Solving & Analytical Thinking

These questions test your ability to deconstruct ambiguous, high-pressure problems and arrive at data-driven solutions.

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?

Diff a projection against the primary without per-row point reads

Hard · reconciliation · range hashing · throttling

The listing projection has drifted and some rows show a stale version. The primary holds 40,000,000 resource rows across 12,000 tenants while serving 1,200 writes and 14,000 reads per second. The obvious repair, reading each resource row and comparing its version against the projection, is correct and would eventually finish. Explain precisely why it is unacceptable here, then give a diff that finds the differing rows, state its complexity, and make it safe to run against a live primary. Replication lag is usually under 100 ms and is not bounded.

Approach

  1. Quantify the naive cost rather than calling it slow: 40,000,000 point reads at even 0.5 ms each is over five hours serialised, and the only lever is concurrency, which is exactly what you cannot spend. The primary's pool is sized for the write path, and 40,000,000 random reads evict the buffer cache that sustains the 85 percent cache hit rate, so the audit degrades the system it is auditing.
  2. Replace random access with one ordered pass per side. Both sides can be read in (tenant_id, resource_id) order, which is a sequential scan on each and a merge join in O(n) time and O(1) memory. For a dense diff that is the whole answer, and it reads the primary once instead of 40,000,000 times.
  3. For the expected sparse case, compare range hashes instead of rows: partition the key space, compute per range an order-independent aggregate over hash(resource_id, version), compare aggregates, and descend only into ranges that differ. With d differing rows and branching factor B, at most d ranges mismatch per level, so the drill-down examines O(d log_B(n/d)) ranges and reads full rows only in mismatching leaves.
  4. Aggregate with a sum modulo 2^64 or a multiset hash, never XOR. XOR is order-independent but self-cancelling, so two rows wrong in the same way, or a row duplicated on one side, leave the range aggregate matching and the range is declared clean.

Follow-up

  • The diff reports 900 stale rows. How do you decide between patching those rows and rebuilding the projection from resource_revision?
  • Same job, but the projection lives in a search index that cannot be scanned in key order. What changes?

Identify the heaviest tenants in a five-minute window under memory pressure

Medium · top-k · heavy hitters · streaming

The edge service handles about 3,000 requests per second across roughly 50,000 tenants, peaking near 9,000. Expose the 50 heaviest tenants by request count over the trailing five minutes so limits can be tightened before one tenant's backfill starves the fleet. You may not retain five minutes of raw records. Give the exact solution and its memory, then the bounded-memory approximation with its error stated as a formula, and say which you would ship and at what tenant cardinality that choice changes.

Approach

  1. Do the exact version first, because it is affordable at this cardinality: a ring of 300 one-second counters per tenant, advanced lazily, is 1,200 bytes of counters per tenant and roughly 60 to 90 MB for 50,000 tenants with overhead. Carry a running total and subtract the bucket you overwrite so a window read is O(1) rather than 300 adds.
  2. Extract the top 50 with a size-k min-heap over the tenant sums: O(d log k) for d tenants, against O(d log d) to sort them all. Maintaining the heap continuously instead of on query requires a tenant-to-heap-index map, because incrementing a count already inside the heap means sifting from a known position, and without that map you rebuild the heap on every request.
  3. State the approximation precisely rather than gesturing at sketches. Misra-Gries with m counters retains every item whose true count exceeds N/(m+1), and each retained count underestimates the truth by at most N/(m+1). With m = 1,000 and N = 900,000 requests in the window the error is roughly 900 requests, which is fine for spotting a tenant sending 50,000 and useless for ranking two tenants 200 apart.
  4. Say what breaks when the window slides: Misra-Gries and Space-Saving are insert-only and cannot be decremented as records age out. The workable construction is one summary per sub-window, say ten seconds, with 30 summaries merged at query time, and the merged error is the sum of the per-summary errors, so the bound degrades linearly in the number of sub-windows.

Follow-up

  • The heaviest tenant is heavy because of one export job rather than user traffic. Should the limiter treat those as the same tenant?
  • Two tenants sit tied at the boundary of the top 50. Does your answer flap, and does the flapping matter?

Replace offset paging on the resource feed with keyset

Easy · keyset pagination · composite index · sort order

resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.

Approach

  1. Name the two failures separately. OFFSET 20000 makes the server produce and discard 20,000 rows, so page cost grows with depth rather than with page size. Independently, any write that changes how many rows sort above the offset moves the window between two fetches, and the direction decides which anomaly you get: an insert lands at the head of updated_at DESC and pushes already-returned rows down past the boundary, so they are returned a second time; a delete above the offset, or a row whose updated_at is bumped above the cursor, pulls rows up and one is never returned at all. Nothing in the response reveals either.
  2. Write the seek: WHERE tenant_id = $1 AND status = 'active' AND (updated_at, resource_id) < ($2, $3) ORDER BY updated_at DESC, resource_id DESC LIMIT 50. The row-value comparison is one index range rather than a disjunction, and both columns are NOT NULL, which is what makes that comparison well defined.
  3. Map each predicate onto the index: tenant_id and status are equality on the leading columns, (updated_at, resource_id) is the range, and the ORDER BY matches the index order so no Sort node appears and the scan stops after 50 rows. The DESC in the definition only matters for mixed directions — a plain ascending btree on the same columns is read backwards for this query.
  4. Put both sort columns in the cursor and nothing the client can tamper with into another tenant: base64 of (updated_at, resource_id), validated server-side, with tenant_id taken from the principal.

Follow-up

  • The client asks for 'jump to page 400'. What do you offer instead, and what does the honest version cost?
  • Sort order becomes user-selectable across four columns. How many indexes is that, and which would you refuse to add?

Explain why the owner filter ignores the listing index

Medium · composite index · query plans · sort elimination

The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.

Approach

  1. Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
  2. For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
  3. Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
  4. Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.

Follow-up

  • 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
  • A dashboard runs this for 40 owners in one page load. What changes about the design?

These questions evaluate your proficiency in software development, your understanding of hardware-software int

Medium · Technical & Domain Knowledge

These questions evaluate your proficiency in software development, your understanding of hardware-software integration, and your grasp of the regulatory standards that govern our industry.

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

  • What happens if the caller retries after a timeout?
  • How does a client discover it is on an old version of this contract?

How do you ensure your code remains robust when running on resource-constrained embedded systems?

Medium · Technical & Domain Knowledge

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?

How do you approach the documentation of software requirements in a regulated environment?

Medium · Technical & Domain Knowledge

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 experience do you have with version control and continuous integration in a team setting?

Medium · Technical & Domain Knowledge

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

  • What happens if the caller retries after a timeout?
  • How does a client discover it is on an old version of this contract?

Explain your process for debugging a complex issue that spans both hardware and software components.

Medium · Technical & Domain Knowledge

Approach

  1. Establish what changed and when, before forming any theory.
  2. Pick a bisection that eliminates candidates whichever way it turns out.
  3. Check the instrumentation before believing the symptom.
  4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

  • What would you look at first, and what would it rule out?
  • How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics DEKA Research & Development candidates report.

Day 1 — Map the DEKA Research & Development loop

  • Write out the reported sequence: Initial Screening, Technical Evaluations, Discussion of Past Projects, Evidence-Based Assessment, Final Evaluation.
  • 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 5 reported rounds, with the weakest marked.

Day 2 — Work Object-Oriented Programming (OOP)

  • Spend the session on Object-Oriented Programming (OOP), which DEKA Research & Development candidates report being tested on.
  • Write one worked example in Object-Oriented Programming (OOP) and time yourself on it.

Deliverable: One timed worked example in Object-Oriented Programming (OOP).

Day 3 — Work PID Control

  • Spend the session on PID Control, which DEKA Research & Development candidates report being tested on.
  • Write one worked example in PID Control and time yourself on it.

Deliverable: One timed worked example in PID Control.

Day 4 — Work Memory Management

  • Spend the session on Memory Management, which DEKA Research & Development candidates report being tested on.
  • Write one worked example in Memory Management and time yourself on it.

Deliverable: One timed worked example in Memory Management.

Day 5 — Answer out loud: Technical & Domain Knowledge

  • Answer aloud, timed: These questions evaluate your proficiency in software development, your understanding of hardware-software integration, and your grasp of the regulatory standards that govern our industry.
  • Answer aloud, timed: How do you ensure your code remains robust when running on resource-constrained embedded systems?

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

Day 6 — Answer out loud: Problem-Solving & Analytical Thinking

  • Answer aloud, timed: These questions test your ability to deconstruct ambiguous, high-pressure problems and arrive at data-driven solutions.
  • Answer aloud, timed: Describe a time you had to diagnose a system failure with limited information; what was your process?

Deliverable: Spoken answers to 2 reported Problem-Solving & Analytical Thinking question(s), under time.

Day 7 — Answer out loud: Behavioral & Collaborative Impact

  • Answer aloud, timed: These questions focus on your ability to work within a team, communicate effectively, and maintain the high standards required at DEKA Research & Development.
  • Answer aloud, timed: Give an example of a time you had to explain a complex technical issue to a non-technical stakeholder.

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

Behavioural preparation

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

Describe a time you had to diagnose a system failure with limited information; what was your process?

Medium · Problem-Solving & Analytical Thinking

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 prioritize tasks when faced with conflicting requirements from different engineering disciplines?

Medium · Problem-Solving & Analytical Thinking

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?

Tell me about a technical trade-off you had to make—how did you justify your decision?

Medium · Problem-Solving & Analytical Thinking

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?

These questions focus on your ability to work within a team, communicate effectively, and maintain the high st

Medium · Behavioral & Collaborative Impact

These questions focus on your ability to work within a team, communicate effectively, and maintain the high standards required at DEKA Research & Development.

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?

Give an example of a time you had to explain a complex technical issue to a non-technical stakeholder.

Medium · Behavioral & Collaborative Impact

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?

Describe a situation where you disagreed with a team member on a technical approach; how did you resolve it?

Medium · Behavioral & Collaborative Impact

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?

What motivates you to work on long-term, complex medical device projects?

Medium · Behavioral & Collaborative Impact

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?