610 questions · from 96 interviews · 15 asked more than once
Oracle interview questions
Every question candidates reported from their Oracle interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
Oracle coding and DSA questions
- 01
Merge Intervals
Given an array of intervals intervals[i] = [starti, endi] , merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input. For example, given [[1,3],[2,6],[8,10],[15,18]] , the output should be…
Medium · Asked 5 times · From Oracle IC3 screening round
- 02
Time Based Key-Value Store
Implement a class TimeMap that supports: - set(string key, string value, int timestamp): Stores the key/value pair along with the given timestamp. - get(string key, int timestamp): Returns the value associated with the key at the greatest timestamp less than…
Medium · Asked 3 times · From Oracle | IC3
- 03
Median of Two Sorted Arrays
Given two sorted arrays, find the median of the combined sorted array in O(log(m+n)) time.
Hard · Asked 3 times · From Oracle Health (IC3 – SMTS) interview experience
- 04
Design LRU Cache
Design and implement a Least Recently Used (LRU) cache with the following operations: - get(key): Return the value of the key if present, otherwise -1. - put(key, value): Insert or update the key-value pair. When the cache reaches capacity, evict the least…
Hard · Asked 2 times · From Oracle | IC3
- 05
Merge Sort Implementation
I was asked to implement the Merge Sort algorithm, demonstrating the code and explaining its working principle.
Medium · Asked 2 times · From Oracle On-Campus
- 06
Longest Substring Without Repeating Characters
Given a string s , find the length of the longest substring without repeating characters. For example, if s = "abcabcbb" , the answer is 3 (for "abc"). If s = "bbbbb" , the answer is 1 (for "b").
Medium · Asked 2 times · From Oracle IC3 screening round
- 07
Divide Two Integers
The problem asks to divide two integers without using multiplication, division, or modulo operators.
Medium · Asked 2 times · From Oracle OCI IC3 (Senior Member of Technical Staff - SMTS) | Bangalore | July 2025 | Selected
- 08
Insert Delete GetRandom O(1)
Solved the Insert Delete GetRandom O(1) problem, focusing on achieving all operations in average constant time using a combination of HashMap and ArrayList.
Asked 2 times · From Oracle OHAI IC3|SDE 3 Interview Experience.
- 09
Top K Frequent Elements
Given an integer array and an integer k, return the k most frequent elements.
Medium · Asked 2 times · From Oracle Oci | IC2 | Bangalore | March 2022 [Offer]
- 10
Remove All Adjacent Duplicates in String II
Given a string s and an integer k , repeatedly delete any group of k identical adjacent characters from the string. Return the final string after no more deletions can be made.
Medium · From Oracle Screening Round: Experience: 5 years | Role: IC3 | Location: Bangalore
- 11
Employee attendance
Given a List<String> of attendance records for n days and an integer m representing the number of employees, determine the number of consecutive days where all m employees were present. Each character in a record is either 'Y' (present) or 'N' (absent).…
From Oracle Screening Round: Experience: 5 years | Role: IC3 | Location: Bangalore
- 12
Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit
Given an integer array nums and an integer limit, return the size of the longest continuous subarray such that the absolute difference between any two elements is less than or equal to limit.
Medium · From Oracle || SDE3 || Interview Experience
- 13
Find Patient-Drug Pairs Prescribed by Different Doctors Within 30 Days
Given sorted prescription records with fields patientId, doctorId, drugName, date, output each patientId drugName pair where the same drug was prescribed to the same patient by at least two different doctors within a 30‑day window. Each pair should be printed…
- 14
Count Distinct Infection Sequences
Given n houses numbered from 0 to n-1 arranged in a straight line and an array infected of initially infected houses on Day 0, each infected house can infect its immediate neighbors (i-1 and i+1) starting the next day. The infection spreads until no more…
From Oracle Senior Software Engineer(IC3) interview experience
- 15
Next Permutation
Given an array of integers, rearrange them into the lexicographically next greater permutation of numbers. If such arrangement is not possible, rearrange to the lowest possible order (sorted in ascending order). I was expected to explain the approach,…
Medium · From Oracle OCI || Software Developer 3 || Phone Screening Round
- 16
Construct an N-ary Tree from Balanced Parentheses
Given a balanced-parentheses string, construct and return the root of an N-ary tree. Each matching () represents a node, and parentheses directly nested inside it represent its children. Example: (()()(()))
From Oracle IC3 interview
- 17
Detect Cycle in Directed Graph
Given a directed graph, determine whether the graph contains a cycle. Return true if a cycle exists, otherwise false.
From Oracle | IC3
- 18
Meeting Rooms II
Given an array of meeting time intervals consisting of start and end times, find the minimum number of conference rooms required. Example: [[0,30],[5,10],[15,20]] = 2 rooms.
Medium · From Oracle | IC3
- 19
Top K URLs overall and in last 24 hours
Given a huge number of URL access logs and limited RAM, determine the top K URLs overall and the top K URLs accessed in the last 24 hours. The interview focused on the approach, trade‑offs, and pseudocode implementation.
Medium · From Oracle | SMTS | Interview Experience
- 20
Top 100 active users in the last hour
Given a stream of events in the format (userId, eventType, timestamp), compute the top 100 users based on event count in the last 1 hour. The discussion included high‑level design choices such as batch vs streaming, Flink vs Spark Streaming, and sliding time…
Medium · From Oracle | SMTS | Interview Experience
- 21
Maximum sum subarray with length constraint
Find the maximum sum of any contiguous subarray whose length is less than or equal to K.
Medium · From Oracle | SMTS | Interview Experience
- 22
Cheapest Flights Within K Stops
Given a set of n cities labeled from 0 to n-1 and a list of flights where each flight is represented as (source, destination, price), find the cheapest price to travel from a starting city src to a destination city dst with at most K stops. If there is no…
Medium · From Oracle Interview Experience
- 23
Maximum of Minimums of Every Window
Given an array A of size n and an integer x, consider every continuous subarray of length x. Find the minimum element in each window and return the maximum among all those minimums. Example: A = [1, 3, -1, 5, 3, 6] x = 3 Windows: [1, 3, -1] - min = -1 [3, -1,…
- 24
SQL - Classify Nodes in a Tree
Given a table with columns id (node ID) and pid (parent ID), classify each node as: - Root: has no parent (pid is NULL) - Inner: has at least one child (its id appears as another row's pid) - Leaf: has no children. Example input: id pid 1 NULL 2 1 3 1 4 2…
- 25
Alphabetically Maximum Substring
Find the alphabetically maximum substring from a given string.
From Oracle | Senior Application Software Engineer | 6+ YOE [Rejected]
243 more in the Oracle write-ups.
Oracle system design questions
- 01
Design a URL Shortener
Design a system that takes a long URL and returns a short alias. The system should support creating short URLs, redirecting to the original URL, handling collisions, and providing analytics.
Hard · Asked 3 times · From Oracle Health (IC3 – SMTS) interview experience
- 02
Previous Project Design Discussion
I had an introduction followed by cross-questioning on the design aspects of my previous projects.
Asked 3 times · From Oracle (OCI) | MTS | India | June'23 | Offer
- 03
SQL vs NoSQL Comparison
Discuss SQL vs NoSQL databases.
Asked 2 times · From OCI | SMTS | Interview experience | Oracle
- 04
Design a Healthcare System
Design a healthcare system for doctors and patients. The discussion covered various components, data flow, entities, APIs, scalability, and data consistency.
Asked 2 times · From Interview Experience - Oracle SMTS
- 05
Design a Temporary Email Service
Design a system that allows users to generate a temporary email address that remains active for 5 hours. The system must support receiving emails during the active period and automatically delete or expire the address and its data after 5 hours. Consider…
- 06
Design a Movie/Concert Booking System
Design a high‑level architecture for a service that allows users to browse, book, and purchase tickets for movies or concerts. Consider aspects such as inventory management, concurrency, payment processing, and scalability.
- 07
Design a system for uploading a 100 GB video
Design a system to handle uploading of very large video files (e.g., 100 GB). Discuss handling of large file uploads, chunking, resumable uploads, storage, and scalability.
From Oracle OCI || Software Developer 3 || Phone Screening Round
- 08
Design URL Shortener
Design a URL shortening service like bit.ly. The system should provide an API to create a short link for a given long URL and redirect users from the short link to the original long URL. Discuss components, database schema, scalability, and handling of…
Hard · From Oracle | IC3
- 09
Design log ingestion system for top K error microservices
Design and implement a system that ingests microservice logs and returns the top K microservices with the highest number of error logs in the last 5 minutes. The interview covered high‑level design, scalability, availability, fault tolerance, and then…
- 10
Log Ingestion System Design
Design a high‑throughput log ingestion system that can collect logs from millions of sources, reliably store them, and make them available for downstream processing and querying. Discuss components such as load balancers, message queues, storage layers,…
- 11
Remote Browser Isolation System Design
Design a remote browser isolation system for enterprises. Discuss authentication, authorization, data streaming, gateways, rate limiting, virtual nodes, edge servers, and any other relevant components.
- 12
Recommendation System for Large-Scale E-commerce
Design a recommendation system for a large-scale e-commerce platform that suggests products to users based on their browsing history and other possible signals.
- 13
Healthcare Data Ingestion Pipeline Design
Design a healthcare data ingestion pipeline capable of processing millions of records efficiently. Discuss data ingestion, queue/message broker selection, storage strategy, processing pipeline, fault tolerance, scalability, monitoring and alerting, and…
- 14
Rate Limiter Design
Design a rate limiter. Discuss different algorithms, caching, distributed implementation, scalability, and trade‑offs.
- 15
File Exporter System
Design a file exporter service that can export data in multiple formats (e.g., CSV, JSON, XML) and supports a factory design pattern for creating format-specific exporters.
- 16
Design an API Gateway
Design an API Gateway that routes incoming requests to appropriate microservices, handles authentication, rate limiting, load balancing, and logging.
- 17
Design a BattlePlayer Game
Java question on design a BattlePlayer game with each player having cards of 3 types and 10 levels. Checking knowledge of interface, abstraction, oops principle.
- 18
- 19
Design an ATM Machine
Design scenario focusing on OOPS fundamentals, Abstraction & Encapsulation with real-time examples, Multithreading (Synchronization, Deadlocks and resolution), Exception handling (Optimizing exceptions in controller layer), and Spring / Spring Boot basics.…
From Oracle OHAI IC3
- 20
When to use SQL vs NoSQL
Discussion on the appropriate use cases for SQL versus NoSQL databases.
From Oracle OHAI IC3
- 21
Handling millions of DB records
Discussion on strategies for efficiently handling millions of database records.
From Oracle OHAI IC3
- 22
Caching strategies
Discussion on various caching strategies to improve system performance.
From Oracle OHAI IC3
- 23
Reducing latency
Discussion on techniques and approaches for reducing system latency.
From Oracle OHAI IC3
- 24
Design a Chat Application (WhatsApp/Slack)
Design a chat application similar to whatsapp/slack (1 hr) - 1B users, 10M DAU - Discussion on API Design, DB choices, guaranteed message delivery
- 25
89 more in the Oracle write-ups.
Oracle behavioural and HR questions
- 01
Behavioral Questions
I was asked several behavioral questions during this round.
Asked 2 times · From Oracle (OCI) | MTS | India | June'23 | Offer
- 02
Describe a Time When You Could Not Meet a Tight Deadline
Behavioural question asking for a specific example where a tight deadline was missed and how it was handled.
- 03
Tell Me About a Conflict Within Your Team and How You Handled It
Behavioural question probing conflict resolution skills.
- 04
Describe a Difficult Technical Decision You Made
Behavioural question focusing on decision‑making under technical constraints.
- 05
How Do You Use AI in Your Daily Work
Behavioural question about the candidate's practical use of AI tools.
- 06
Opinion on AI and Its Impact on Software Engineering
Behavioural question asking for the candidate's perspective on AI advancements in software development.
- 07
Tell me about a conflict you had
Tell me a time when you had conflict
- 08
Making Others Welcome in a Team
How did you make others welcome in a team?
- 09
Dealing with Unresponsive Project Managers
How did you deal with someone not responding to the problems you are working e.g. Project managers not clarifying on tasks specification
- 10
Describe a Mistake and Learning
Tell me a mistake that you made and what did you learn?
- 11
Deviating from Protocol
Did you ever go out of the way without following the protocol to design your solution.
- 12
Untestable Problems and Testing Strategies
Tell me about a situation when the problem was untestable? What did you do for testing?
- 13
- 14
- 15
Managing Conflict with a Team Member
How did you manage conflict with a team member?
- 16
Innovations done in project
Behavioral question asking about innovations done in a project.
From Oracle OHAI IC3
- 17
Business improvements suggested
Behavioral question asking about business improvements suggested.
From Oracle OHAI IC3
- 18
General team and ownership questions
Behavioral questions related to team dynamics and ownership.
From Oracle OHAI IC3
- 19
Most Critical Bug
Describe your most critical bug and how you handled it.
- 20
Increase Team Productivity
What have you done to increase the productivity of the team?
- 21
Career Motivation and Choices
what is ICE? Why NITT? Why do something that is not your core? Why interested in CS?
- 22
Teamwork Experience
what was my experience in working in a team.
- 23
Describe a Mistake and Resolution
Describe a time when you made a mistake and explain how you fixed it.
From Oracle ic4
- 24
Overcoming Lack of Understanding
Describe a time where you were working on something you didn't understand anything, and how you managed to overcome that challenge.
From Oracle ic4
- 25
Describe Yourself Beyond Resume
Tell me something not in your resume that defines who you are. This could be a hobby, a passion, or a characteristic not evident from your professional experience.
48 more in the Oracle write-ups.
Oracle other questions
- 01
Search in Rotated Sorted Array
Given a sorted array that has been rotated at some pivot unknown, find the index of a given target. The array may contain duplicates.
Medium · Asked 2 times · From Oracle | IC4 | Interview Experience | Ghosted by HR
- 02
Static Method Behavior in Java
A question or discussion regarding the behavior and characteristics of static methods in Java.
From Oracle | Senior Application Developer | Feb 2026 | Rejected
- 03
Calculate Time Difference Between Local DateTimes
A question concerning how to calculate the time difference or duration between two LocalDateTime objects in Java, likely involving the Duration class.
From Oracle | Senior Application Developer | Feb 2026 | Rejected
- 04
Describe a recent project where you contributed to design
Question about a recent project where I contributed to design.
From Oracle OHAI IC3
- 05
SOLID principles and design patterns discussion
Discussion covering SOLID principles and various design patterns.
From Oracle OHAI IC3
- 06
1000 Wine Bottles and 10 Rats Puzzle
You have 1000 bottles of wine. One of the bottles is poisoned. You have 10 rats. A rat dies exactly one hour after drinking from the poisoned bottle. How do you find the poisoned bottle in one hour?
Hard · From Senior Application Engineer | Oracle interview experience | Feb 2026
- 07
Java Exception vs. Error and specific exception types
Discuss the difference between an exception and an error in Java. Explain NoClassDefFoundError and ClassNotFoundException.
From Senior Application Engineer | Oracle interview experience | Feb 2026
- 08
Paging vs. Segmentation & Fragmentation
difference between paging and segmentation, what is fragmentation, where does internal fragmentation happen.
- 09
Polymorphism in OOP
oops question. About polymorphism, its types and some examples.
- 10
Maximum Product of Three Numbers
Given an integer array, find three numbers such that their product is maximum. The array can contain negative numbers, zeros, and positive numbers.
Medium · From Oracle | IC4 | Interview Experience | Ghosted by HR
- 11
Explain TCP and UDP
Describe what TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are, highlighting their fundamental differences and characteristics.
- 12
TCP vs UDP Use Cases
When do we use TCP and when UDP? Provide examples of scenarios where each protocol is more suitable and explain the reasoning behind your choices.
- 13
HTTP Status Codes
Discuss the significance of HTTP Status Codes. Provide examples of common status codes and explain their meanings (e.g., 200, 404, 500).
- 14
Gold Rod Payment Puzzle
An employee works for 7 days. The employer has a gold rod of 7 units. How does the employer pay the employee 1 unit at the end of each day? Maximum 2 cuts allowed.
- 15
Types of Constructors
Explain the different types of constructors found in object-oriented programming (e.g., default, parameterized, copy constructor), and when each type is typically used.
- 16
Virtual Functions
What is a Virtual Function? Explain its purpose, how it's implemented (e.g., in C++), and its role in achieving polymorphism.
- 17
Favorite Data Structure Discussion
Which data structure do you like more and why? Discuss your preferred data structure, its advantages, disadvantages, and common use cases.
- 18
SQL Joins
Explain different types of Joins in SQL (e.g., INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN). Describe their functionality and provide examples of when to use each.
- 19
Kth Minimum Salary SQL Query
Write a SQL query to find the Kth minimum salary from a table. Assume you have an 'employees' table with a 'salary' column.
- 20
Duplicate Class Names in JAR
What happens when you have same-named classes in a JAR file and you call that class? Explain the class loading mechanism in such a scenario.
- 21
Fair Cake Sharing Puzzle
You and I have a cake. I took some uneven part from it. Now your friend comes. How can you both share the remaining cake equally?
- 22
Blindfolded Coin Split
Given 10 coins, some heads and some tails. You are blindfolded and need to split them into two groups such that both groups have an equal number of heads (or tails).
From Oracle interview | Fresher | Application Developer | IC-2 level
- 23
Equilateral Triangles with 6 Matchsticks
Determine the number of equilateral triangles that can be formed using exactly 6 matchsticks.
From Oracle interview | Fresher | Application Developer | IC-2 level
- 24
Nth Highest Salary with Table Joins
Given employee salary data across multiple tables, join them and find the Nth highest salary. Discuss different approaches to solve this problem.
From Oracle interview | Fresher | Application Developer | IC-2 level
- 25
Convert Percentage to Grades
Given a table with percentages, convert them into corresponding grades. Initially, a CASE statement approach was discussed. A follow-up asked to achieve this without using a CASE statement, for example, by creating a separate grades lookup table and joining.
From Oracle interview | Fresher | Application Developer | IC-2 level
130 more in the Oracle write-ups.
Oracle interview questions FAQ
What questions are asked in Oracle interviews?
Candidates reported 610 distinct questions across 96 Oracle interviews. 268 coding and DSA questions, 114 system design questions, 73 behavioural and HR questions, 155 other questions.
Which Oracle interview questions are asked most often?
The most repeated are "Merge Intervals" (5 times), "Time Based Key-Value Store" (3 times), "Median of Two Sorted Arrays" (3 times), "Design a URL Shortener" (3 times), "Previous Project Design Discussion" (3 times).
How difficult are Oracle interview questions?
Of the questions candidates rated, 21% were easy, 57% medium and 22% hard.