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Interview guides · Blue Cross and Blue Shield of Kansas

Blue Cross and Blue Shield of Kansas Software Engineer Interview Guide

Blue Cross and Blue Shield of Kansas Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

The role of a Software Engineer at Blue Cross and Blue Shield of Kansas is pivotal in driving the technological backbone of healthcare solutions. As a Software Engineer, you will contribute to the development, enhancement, and maintenance of applications that not only streamline healthcare processes but also ensure compliance with industry standards. Your work will directly impact millions of members by improving the efficiency and effectiveness of healthcare delivery. This role is critical as you will be part of a dynamic team that tackles complex challenges in the healthcare domain. You will work on a variety of projects, from optimizing existing systems to developing innovative software solutions that meet the evolving needs of healthcare providers and members.

This guide is scoped to a Software Engineer candidate at Blue Cross and Blue Shield of Kansas.

Focus areas

  • OOP (Object-Oriented Programming)
  • SQL
  • Coding (Writing Code in Interview)

The Blue Cross and Blue Shield of Kansas interview process

Blue Cross and Blue Shield of Kansas candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Phone Screening

Initial screening call to assess candidate's background and fit for the role.

What to demonstrate

  • Initial screening call to assess candidate's background and fit for the role
  • Depth in OOP (Object-Oriented Programming)

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 complete technical coding challenges to demonstrate their skills.

What to demonstrate

  • Candidates complete technical coding challenges to demonstrate their skills
  • Depth in OOP (Object-Oriented Programming)

How to prepare

  • Answer aloud and timed: Describe a time you had to troubleshoot a complex issue in your code.
  • Answer aloud and timed: What are the key principles of RESTful API design?

Behavioral Evaluation

Discussion around past experiences and teamwork potential with team members.

What to demonstrate

  • Discussion around past experiences and teamwork potential with team members
  • Depth in OOP (Object-Oriented Programming)

How to prepare

  • Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
  • Re-read the description of the behavioral evaluation above and write down what you would ask to confirm before it.

In-Person Interview

Final interviews that may include multiple rounds of discussions and assessments.

What to demonstrate

  • Final interviews that may include multiple rounds of discussions and assessments
  • Depth in OOP (Object-Oriented Programming)

How to prepare

  • Answer aloud and timed: How do you prioritize tasks when working on multiple projects?
  • Answer aloud and timed: Give an example of how you have worked effectively in a team.

Where candidates lose points

Showcase Your Projects

Prepare to discuss personal or professional projects that highlight your skills and experience. This demonstrates your passion for software engineering.

Practice Coding

Engage in coding exercises and practice coding challenges to sharpen your skills before the interview.

Understand the Healthcare Domain

Familiarize yourself with the healthcare industry, as this knowledge can set you apart.

Be Ready for Behavioral Questions

Prepare examples from past experiences that illustrate your problem-solving and teamwork abilities.

Questions & practice

How do you manage memory in a programming language you are familiar with?

Medium · Technical / Domain Questions

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?

Write a function to reverse a string in your preferred programming language.

Medium · Coding / Algorithms

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?

Given a list of integers, write a function to find the maximum product of two integers.

Medium · Coding / Algorithms

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?

Explain your approach to solving a dynamic programming problem.

Medium · Coding / Algorithms

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?

How would you implement a binary search algorithm?

Medium · Coding / Algorithms

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?

Write a function to check if a string is a palindrome.

Medium · Coding / Algorithms

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?

Explain how you would optimize a SQL query.

Medium · Technical / Domain Questions

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?

Denormalise tenant onto revisions and backfill it live

Hard · denormalisation · online migration · backfill

resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.

Approach

  1. Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
  2. Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
  3. Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
  4. Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.

Follow-up

  • The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
  • How do you verify the backfill actually finished, given rows are still being inserted while it runs?

Explain the differences between object-oriented programming and functional programming.

Medium · Technical / Domain Questions

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 are the key principles of RESTful API design?

Medium · Technical / Domain Questions

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?

Edge instances grow 400 MB per hour until the nightly restart

Hard · memory leak · heap analysis · metric cardinality

Edge API instances start at 700 MB resident and grow about 400 MB/hour; a nightly rolling restart has hidden it for weeks. Growth continues unchanged when request rate halves overnight, p99 degrades in the last hours before an instance is recycled, and heap used immediately after a forced full GC rises monotonically. The service holds no product state. Name the discriminating measurement that separates the plausible causes, give the most likely cause, and give the fix and how you would verify it.

Approach

  1. Separate resident memory from live heap first, because they fail differently. Resident size can grow from fragmentation, native buffers or thread stacks while the heap is flat; heap used after a full GC rising monotonically is the measurement that says objects are reachable and not being released. You already have it, so this is retention, not fragmentation, and that closes off half the candidate list.
  2. Use the rate's independence from traffic as the discriminator. Growth that continues at half the request rate rules out per-request objects that are merely slow to collect and points at a structure that grows with distinct values observed rather than with call volume. Write the candidates that have that property: a metrics registry keyed on a high-cardinality label, an unevicted cache, an interner, a per-key lock map.
  3. Take two heap snapshots an hour apart and diff by retained size, reading the dominator tree, not by allocation count or instance count. Expect one root holding a map with millions of entries, then follow the reference chain to the code that inserts and never removes. Allocation profilers point at churn, which is the wrong signal here.
  4. The candidate that fits this service is an observability label carrying an identifier, such as a request path recorded before templating so that /v1/resources/48213 becomes its own metric series. That grows with distinct ids seen, is independent of rate, and explains the late p99 degradation, since GC cost rises with the size of the live set.

Follow-up

  • Post-GC heap is now flat but resident size still creeps. What are you looking at, and does it matter?
  • How would you have detected this before an OOM, given the nightly restart masked the trend?

Suggested practice checklist

Built from the rounds and topics Blue Cross and Blue Shield of Kansas candidates report.

Day 1 — Map the Blue Cross and Blue Shield of Kansas loop

  • Write out the reported sequence: Phone Screening, Technical Assessment, Behavioral Evaluation, In-Person Interview.
  • 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 OOP (Object-Oriented Programming)

  • Spend the session on OOP (Object-Oriented Programming), which Blue Cross and Blue Shield of Kansas candidates report being tested on.
  • Write one worked example in OOP (Object-Oriented Programming) and time yourself on it.

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

Day 3 — Work SQL

  • Spend the session on SQL, which Blue Cross and Blue Shield of Kansas candidates report being tested on.
  • Write one worked example in SQL and time yourself on it.

Deliverable: One timed worked example in SQL.

Day 4 — Work Coding (Writing Code in Interview)

  • Spend the session on Coding (Writing Code in Interview), which Blue Cross and Blue Shield of Kansas candidates report being tested on.
  • Write one worked example in Coding (Writing Code in Interview) and time yourself on it.

Deliverable: One timed worked example in Coding (Writing Code in Interview).

Day 5 — Answer out loud: Technical / Domain Questions

  • Answer aloud, timed: Explain the differences between object-oriented programming and functional programming.
  • Answer aloud, timed: How do you manage memory in a programming language you are familiar with?

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

Day 6 — Answer out loud: Behavioral / Leadership Questions

  • Answer aloud, timed: Can you describe a challenging project and how you handled obstacles?
  • Answer aloud, timed: How do you prioritize tasks when working on multiple projects?

Deliverable: Spoken answers to 2 reported Behavioral / Leadership Questions question(s), under time.

Day 7 — Answer out loud: Coding / Algorithms

  • Answer aloud, timed: Write a function to reverse a string in your preferred programming language.
  • Answer aloud, timed: Given a list of integers, write a function to find the maximum product of two integers.

Deliverable: Spoken answers to 2 reported Coding / Algorithms question(s), under time.

Behavioural preparation

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

Describe a time you had to troubleshoot a complex issue in your code.

Medium · Technical / Domain Questions

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?

Can you describe a challenging project and how you handled obstacles?

Medium · Behavioral / Leadership Questions

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 working on multiple projects?

Medium · Behavioral / Leadership Questions

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 how you have worked effectively in a team.

Medium · Behavioral / Leadership Questions

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 succeed in your role?

Medium · Behavioral / Leadership Questions

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 feedback and criticism?

Medium · Behavioral / Leadership Questions

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?