Oracle OCI IC2/IC3 Interview Experience — Bangalore, 2022

How the process went

1. Round 1 — HLD/LLD

   A 60-minute system design round: design a parking lot system similar to Uber, where users see available spaces across nearby lots based on location, with early booking, geofencing, disabled-user allocation, peak-traffic handling, and database choice all in scope. Low-level design was expected as well, and the interviewer changed requirements partway through.

2. Round 2 — Hiring Manager

   A conversation about the interviewer's team and products, what the candidate could expect to work on, and a detailed walkthrough of the candidate's most recent project (design, problem statement, API success rates, efficiency gains). Also covered database selection, ACID properties, project management, and why the candidate wanted to switch companies.

3. Round 3 — DSA / Project Discussion

   The candidate explained their current project using the STAR method, then solved two LeetCode-style string problems, followed by a few behavioral questions.

4. Round 4 — DSA / HLD / Behavioral

   Questions on the microservices in the candidate's current project and the full process flow, behavioral questions on leading a team, and a coding problem involving conditional directive processing solved with a stack.

5. Round 5 — DSA / System Design / Behavioral

   Questions on choosing a tech stack, the CAP theorem, and ACID isolation, plus a sliding-window coding problem on counting permutation substrings.

6. Outcome

   The candidate received an offer.

Round 1 — HLD/LLD Round

System design for a location-aware parking lot platform, with both high-level and low-level design expected · 60 minutes

• Design a parking lot system similar to Uber, where users can see available spaces across nearby lots based on their current location.
• How would you support early booking of a parking spot?
• How would you use geofencing to show the user the nearest lot with available spaces?
• How would you allocate specific spaces for users with disabilities?
• How would you handle traffic at peak times (e.g., load balancers, optimized algorithms)?
• If traffic is high and an accessible space is available, how would you handle that allocation?
• How would you verify that the customer entering is the one who made the booking?
• How would you automate the parking lot process end-to-end?
• Which database would you use, and why?

The interviewer changed the functional requirements partway through the discussion, so the candidate noted it helps to design with some flexibility for new changes.

A low-level design was expected in addition to the high-level design.

Round 2 — Hiring Manager Round

Team and project fit, a deep dive on the candidate's most recent project, and database fundamentals

• Walk through your most recent project in detail, including the design, problem statement, API success rates, and how you improved the system's efficiency.
• How do you choose a database for a project? (CAP theorem-based reasoning was expected.)
• What is the ACID property? Explain isolation and durability.
• How do you manage a project that is too large to complete within a set timeframe?
• Which languages have you worked with?
• Why are you looking to change companies?

The interviewer also described his team and the products they work on, and what the candidate could expect to work on after joining.

Additional behavioral questions were asked that were not detailed in the original post.

Round 3 — DSA / Project Discussion Round

A structured walkthrough of the candidate's project plus two string-based coding problems

• Explain your current project using the STAR method.
• Valid Parentheses (leetcode.com/problems/valid-parentheses/)
• Longest Valid Parentheses (leetcode.com/problems/longest-valid-parentheses/)

A few behavioral questions were asked at the end of the round.

Round 4 — DSA / HLD / Behavioral Round

Architecture of the candidate's current project, leadership behavioral questions, and a coding problem

• What microservices exist in your current project?
• Describe the full flow of the process.
• Behavioral questions on leading a team and handling issues.
• Given a sequence of strings and a map of flags (containing #ifdef/#ifndef/#endif-style directives, e.g. a map like {FOO: true, BAR: true}), print only the strings whose enclosing conditional evaluates to true.

The candidate solved the conditional-directive problem using a stack to track the active flag for each nested if-block.

Round 5 — DSA / System Design / Behavioral Round

Tech stack decisions, database theory, and a sliding-window coding problem

• How do you decide the tech stack for an application you're starting?
• Explain the CAP theorem.
• Explain the isolation property of ACID.
• Given a string 'logs' and a string 'password', find the number of substrings of logs that are a permutation of password.

The candidate solved the substring-permutation problem using a sliding window approach.

The candidate noted that OCI interviewers seemed to value a working solution even if it wasn't the most optimal one, and suggested writing a working approach first before optimizing when time is limited.

Source

The questions and process facts come from the candidate's public write-up, linked below. The retelling above is our own summary.