30 questions · from 3 interviews
Tripjack interview questions
Every question candidates reported from their Tripjack interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
Tripjack coding and DSA questions
- 01
Jump Game II
LeetCode problem 45: Given an array of non‑negative integers where each element represents your maximum jump length at that position, determine the minimum number of jumps required to reach the last index.
Medium · From Tripjack SDE-1 Interview Experience
- 02
Zigzag Conversion
LeetCode problem 6: Convert a given string to a zigzag pattern on a given number of rows and then read line by line.
Medium · From Tripjack SDE-1 Interview Experience
- 03
Number of Islands
LeetCode problem 200: Given a 2D grid of '1's (land) and '0's (water), count the number of distinct islands where an island is formed by horizontally or vertically adjacent lands.
Medium · From Tripjack SDE-1 Interview Experience
- 04
Implement a Singleton class
Write a Java class that follows the Singleton design pattern, ensuring only one instance can be created.
- 05
Optimize Singleton with synchronized and lazy loading
Improve the Singleton implementation by adding synchronized lazy initialization to ensure thread‑safety.
- 06
Further optimize Singleton with inner/block‑level synchronization
Refactor the Singleton using inner static holder class or double‑checked locking for better performance.
- 07
Kth Largest Number in an Array
I was asked to find the Kth largest number in an array.
- 08
Trapping Rain Water
I was asked the 'Trapping Rain Water' problem.
- 09
Remove K Digits to Form Largest Number
Given a non-negative integer represented as a string num , and an integer k , remove k digits from the number so that the new number is the largest possible. I was specifically asked for the largest number, unlike the common variation that asks for the…
Medium · From TripJack | Round 2 | Virtual | SDE-3
Tripjack system design questions
- 01
Design a Message Queue
I had to design a message queue capable of handling 1 billion events per second. The focus was primarily on Low-Level Design (LLD) rather than High-Level Design.
Hard · From TripJack | Lead Engineer | Delhi
- 02
System Design: Collaborative Environment (Google Docs/OneDrive)
Design the system for a collaborative environment similar to Google Docs or OneDrive. The discussion's primary focus was on the architecture concerning how files are stored at the server level and the strategies implemented to resolve conflicts that arise…
Tripjack behavioural and HR questions
- 01
Introduce yourself
Tell the interviewer about your background, experience and key strengths.
Tripjack other questions
- 01
Explain JWT
Provide an explanation of JSON Web Token, its structure, usage, and typical workflow.
- 02
Explain Java 8 features
Discuss major features introduced in Java 8 such as lambda expressions, streams, default methods, and Optional.
- 03
What is indexing
Explain the concept of indexing in databases and its purpose for speeding up data retrieval.
- 04
Clustered vs non‑clustered index
Define clustered and non‑clustered indexes, their differences, and when each should be used.
- 05
What is the synchronized keyword
Describe the purpose of the synchronized keyword in Java and how it provides mutual exclusion.
- 06
What is HTTP/2
Explain the main improvements of HTTP/2 over HTTP/1.1, such as multiplexing, header compression, and server push.
- 07
Explain Bill Pugh Singleton method
Describe the Bill Pugh approach for implementing a Singleton using a static inner helper class.
- 08
Why is Kafka used
Explain the reasons for using Apache Kafka such as high throughput, fault tolerance, and pub‑sub messaging.
- 09
Ensuring same keys go to same Kafka partition
Describe how Kafka’s partitioner uses the message key's hash to route records with the same key to the same partition.
- 10
Explain multithreading concepts
Cover basics of multithreading in Java including thread lifecycle, runnable vs callable, and thread pools.
- 11
Explain TCP three‑way handshake
Detail the SYN, SYN‑ACK, ACK sequence used to establish a TCP connection.
- 12
Explain ConcurrentHashMap working
Discuss the internal structure of Java’s ConcurrentHashMap, segment locking and lock‑striping mechanisms.
- 13
Types of locks
List and briefly describe different lock types such as optimistic, pessimistic, read/write, and reentrant locks.
- 14
Optimistic vs pessimistic locking
Compare optimistic and pessimistic locking strategies, their use‑cases and trade‑offs.
- 15
What is GraphQL
Provide an overview of GraphQL, its query language, type system, and advantages over REST.
- 16
Explain project architecture (payment gateway)
Describe the overall architecture of my payment gateway project, including services, databases, and communication patterns.
- 17
Explain working of APIs
Explain how APIs function, covering request/response flow, status codes, authentication, and versioning.
- 18
Explain design patterns
Discuss common software design patterns such as Singleton, Factory, Observer, and Strategy, and their typical use‑cases.
Tripjack interview questions FAQ
What questions are asked in Tripjack interviews?
Candidates reported 30 distinct questions across 3 Tripjack interviews. 9 coding and DSA questions, 2 system design questions, 1 behavioural and HR questions, 18 other questions.
How difficult are Tripjack interview questions?
Of the questions candidates rated, 0% were easy, 80% medium and 20% hard.