169 questions · from 40 interviews · 14 asked more than once
PhonePe interview questions
Every question candidates reported from their PhonePe interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
PhonePe coding and DSA questions
- 01
Burst Balloons
I was asked to solve the Burst Balloons problem.
Hard · Asked 4 times · From Phonepe Interview Experience | 6 YOE | SDE-III
- 02
Kth Smallest Element in a Sorted Matrix
Find the k‑th smallest element in an n × n matrix where each row and each column is sorted in ascending order.
Medium · Asked 3 times · From Phonepe YOE 5
- 03
Remove K Digits
Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.
Medium · Asked 3 times · From PhonePe Prep
- 04
Min Stack
Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
Medium · Asked 2 times · From PhonePe || SE (1-3Y) || Interview Experience
- 05
Burning Tree
Find the minimum time taken to burn the entire binary tree starting from a given target node.
Medium · Asked 2 times · From PhonePe Prep
- 06
Shortest Path to Get All Keys
Given a 2D grid consisting of walls, empty cells, the starting point, keys, and locks. Return the shortest path to get all keys.
Hard · Asked 2 times · From PhonePe Prep
- 07
Maximum Profit in Job Scheduling
Given n jobs where startTime[i], endTime[i], and profit[i] are the start time, end time, and profit of the i-th job, return the maximum profit you can achieve by scheduling jobs such that no two jobs overlap.
Hard · Asked 2 times · From PhonePe Prep
- 08
Determine if Two Strings Are Close
Two strings are considered 'close' if you can attain one from the other using two types of operations: 1. Swap any two existing characters. 2. Transform every occurrence of one existing character into another existing character, and vice versa. Return true if…
Medium · Asked 2 times · From PhonePe Prep
- 09
Matchsticks to Square
You are given an integer array matchsticks where matchsticks[i] is the length of the i-th matchstick. You want to use all the matchsticks to form one square. You should not break any single matchstick, but you can link them up, and each matchstick must be…
Medium · Asked 2 times · From PhonePe Prep
- 10
The Celebrity Problem
In a group of N people, a celebrity is someone who is known by everyone else but does not know anyone. Find the celebrity if one exists.
Medium · Asked 2 times · From PhonePe Prep
- 11
Rotting Oranges
You are given an m x n grid where each cell can have one of three values: 0 representing an empty cell, 1 representing a fresh orange, or 2 representing a rotten orange. Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange…
Medium · Asked 2 times · From PhonePe Prep
- 12
Daily Temperatures
Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the i-th day to get a warmer temperature. If there is no future day for which this is possible,…
Medium · Asked 2 times · From PhonePe Prep
- 13
Journey Service Machine Coding
Multiple journeys, each journey has multiple stages. A user starts from the first stage of the journey and moves to the next stage when a new event arrives and if the stage criteria is met. Follow‑up questions on concurrency were also asked.
From Phonepe YOE 5
- 14
Evaluate Division
Given a list of equations like a / b = 2.0 and queries, evaluate the division results for each query.
Medium · From Phonepe YOE 5
- 15
Identify Two Failing Test Cases with Minimal Calls
Given N test cases where exactly two are failing, you can query a black‑box function testSuite(listoftestids). The function returns FAIL if both failing test cases are present in the supplied list, otherwise it returns PASS. The goal is to determine the…
From PhonePe || Backend (3-5 years) || Interview Experience – Software Engineer Interview Experience
- 16
Sequential Task Assignment with Context Switching Cost
Problem Logic: You have a sequence of K total task slots. For each slot i, you can choose to work on a task from Startup A or Startup B, each yielding a specific payout. Constraints: 1. You can complete at most M tasks in total. 2. Switching from A to B (or B…
- 17
Substring Count Excluding Specific Subsequences
Problem Logic: Given a master string S (representing a sequence) and a smaller target pattern string T, you need to evaluate all contiguous substrings of S. Conditions: A contiguous substring is invalid if string T appears inside it as a subsequence (meaning…
- 18
Constrained Jump Sequences to a Target Point
Problem Logic: There are N discrete locations along a straight line, numbered 1 to N. You start at location A and need to make a sequence of exactly K consecutive jumps. A fixed spotlight is stationed at location B. Movement Rules: 1. You cannot land on the…
- 19
Count Bowl Subarrays
Solve the LeetCode problem "Count Bowl Subarrays". The exact problem statement can be found at the linked URL.
- 20
Reconstruct Itinerary
Solve the LeetCode problem "Reconstruct Itinerary". The exact problem statement can be found at the linked URL.
- 21
HackAthon Platform Machine Coding
The problem statement was to build a HackAthon Platform. The candidates were asked to solve it on their own within 1.5 hours, then share the code in a zip file to the recruiter. An evaluation call followed for about 30 minutes to discuss the implementation.
- 22
Sliding Window Maximum
I was asked to solve the Sliding Window Maximum problem.
Hard · From Phonepe Interview Experience | 6 YOE | SDE-III
- 23
Water Jug Problem
The classic Water Jug Problem.
- 24
Binary Tree Mirror Image Problem
A problem related to binary trees and determining their mirror image.
- 25
Find Logical Bug in Code
Given ~100 lines of code, the candidate was asked to find bugs. Apart from all technical bugs, a logical bug was identified which the interviewer appreciated.
From My Interview Journey: Rejections, Grind, and an Unexpected Tier-1 Offer
85 more in the PhonePe write-ups.
PhonePe system design questions
- 01
Design Instagram
Design Instagram, focusing on core features like posting content, immediate post visibility, feed generation, and likes/comments. I covered non-functional requirements, set scale expectations, and outlined a high-level design, detailing each service and its…
Hard · Asked 3 times · From PhonePe Prep
- 02
Design Delayed Trigger Service
Design a service that registers triggers with specified delays from other services and sends a response once the delay for that trigger is completed.
Asked 2 times · From PhonePe Prep
- 03
Feature Flag System Design
Design a feature flag system for PhonePe where any change in a flag propagates instantly to millions of users. References were provided to videos describing similar systems.
From Phonepe YOE 5
- 04
Design Job Scheduler
Design a job scheduler system, covering aspects such as architecture, scalability, latency considerations, and trade‑offs.
- 05
Notification Service LLD
Design a low‑level component for a notification service, discussing its modules, data flow, and reliability considerations.
- 06
Smart Home Automation System Machine Coding
Description To build an IoT based Home Automation System Home Features An Interface device Google Home Alexa More can be added An SmartHome device Generic Electrical Devices &9702; Can be turned on and off Lights &9702; Can be turned on and off &9702;…
Hard · From PhonePe SDE 2 MAchine coding
- 07
Design Order Feed System
Design an order feed system for a food ordering app where users can see real-time updates to their orders. Requirements: Different category services involved in order path publish real-time context data into feed service under a global orderId during the…
- 08
Customer Issue Resolution System Design
Design a system for Customer Issue Resolution involving Agents and Issues. Issues will have types such as payment failure, query, etc. The focus was on the user assignment strategy.
- 09
Design Search Autocomplete Feature
Design a search autocomplete feature. I used a Trie data structure and implemented a working solution. The discussion covered scalability, handling different scenarios, and optimization of memory and time complexity.
From PhonePe Prep
- 10
Design an Online Game (e.g., Ludo/Chess/SnakeNladder)
Design an online multiplayer game like Ludo or Chess. I had to lead the discussion, covering functional and non-functional requirements, high-level design, APIs, tech stack choices, implementation details, exception handling, fault tolerance, and database…
From PhonePe Prep
- 11
Design Payment Gateway Integration
Design a system for payment gateway integration. The interviewers were looking for very specific details in the design.
From PhonePe Prep
- 12
Design Twitter
Design Twitter, focusing on functionalities such as posting tweets, follow/following mechanisms, user timelines, and user profiles. The interview emphasized both Low-Level Design (LLD) and High-Level Design (HLD).
From PhonePe Prep
- 13
App Version Management System Design
App Version Management System Every smartphone user these days has lots of apps installed in their smartphones. These apps follow multiple iterations in its lifecycle which can range from fresh installs to updates of an existing app. Install is done for cases…
Hard · From PhonePe Machine Coding Round
- 14
Design a Fitness Class Booking System
Design a Fitness Class Booking System with the following features: 👥 User Management: Users can register/login with tier-based packages: Platinum → 10 classes Gold → 5 classes Silver → 3 classes 📅 Class Management (Admin Functionality): Create, schedule,…
Hard · From 🏢 PhonePe Machine Coding Round – SDE Interview Experience
- 15
Instagram News Feed
Design Instagram news feed
From Phonepe Interview Experience (Software engineer 3-5Yoe)
- 16
Design Blinkit
Design blinkit. High variation in number of users of users and number of dark store per square area.
- 17
Design a Hackathon Platform Backend
PhonePe is conducting its annual hackathon and wants to create an interactive platform to host the event. It will be a 2 day event and contestants need to maximize their score over this period by either solving more problems or more difficult problems. Design…
Hard · From PhonePe Machine Coding Question
- 18
Design and Implement an Advertisement Engine (Machine Coding)
Design and implement an advertisement engine. The system manages Advertisers, Ads, and User Ad requests. It must select and serve the most relevant Ad based on matching criteria, bidding amount, and system constraints while respecting budget constraints.…
Hard · From PhonePe | SDE2 | Machine Coding Round
- 19
Design a Payment Gateway System
I was asked to create a working code of a Payment Gateway System with multiple related features. A reference was provided.
- 20
Design Search Autocomplete with Trie
I was asked to design a Search Autocomplete feature. Trie data structure needs to be used. Discussion included scalability, handling different scenarios, and optimization of memory and time complexity.
- 21
E-Commerce App Design with Data Sync
I was given a problem to design an E-Commerce app and manage data between different screens. The data also needed to be synced with backend servers. I had 90 minutes to complete 4-5 criteria/features with scalable and clean code.
From PhonePe Interview Experience | Offer | Accepted | SDE(Android) | Bengaluru
- 22
Design a Map App
An open-ended question to design a map app. I had to describe an optimal approach that could be transformed into a market-ready application.
From PhonePe Interview Experience | Offer | Accepted | SDE(Android) | Bengaluru
- 23
System Design: Shazam (HLD)
Design the Shazam application, focusing on High-Level Design (HLD).
Hard · From Phonepe Software Engineer | Reject
- 24
Design and Implement a Fitness Class Booking System
Objective: Design and implement an application to allow users to choose and book fitness classes. The application should cater to user management, class scheduling, and booking, including waitlisting and cancellation features. Requirements: User Management:…
Hard · From PhonePe | Software Engineer (Backend) | Machine Coding
- 25
Design a Complaint Resolution System
Design a complaint resolution system to manage unsuccessful transactions. Key features include: Customers can log issues for failed or pending transactions by providing details like issue type, subject, description, and email. Customer Service Agents: Handle…
Hard · From PhonePe | SDE2 | Machine Coding Round
13 more in the PhonePe write-ups.
PhonePe behavioural and HR questions
- 01
Behavioral and Situational Questions
The interview included general behavioral and situational questions designed to assess problem-solving skills, teamwork, handling conflict, and career aspirations.
- 02
- 03
Why are you changing companies?
Why changing company
- 04
- 05
Current Company Project Discussion
Current company project discussion in detail. What and why in current company project
- 06
Behavioral and Agile Methodology Questions
I was asked about my reasons for looking for a change and other behavioral questions, including topics related to agile methodologies.
- 07
Behavioral Questions
The Hiring Manager asked some really tough behavioral questions.
From PhonePe Interview Experience | Offer | Accepted | SDE(Android) | Bengaluru
- 08
- 09
Challenges Faced in Previous Roles
Describe challenges I faced in my previous jobs and how I addressed them.
- 10
Ideal Team and Conflict Resolution
Discuss the ideal team I desire, issues I face in my current team and company, and how to resolve them.
PhonePe other questions
- 01
Generate Random Points in Circle with Equal Probability
Write a function that generates random points within a circle with equal probability distribution.
Medium · From PhonePe Prep
- 02
Design Battleship Game
Design and implement a battleship game to be played between two players until one comes out as the winner. A player wins When all the ships of his opponent has been destroyed. Missiles are fired randomly and they should not be fired at the same location twice.
- 03
Machine Coding: Pendency System
Implement a machine coding pendency system.
- 04
Find Faster Rat (Puzzle)
You have 12 rats. One rat eats faster than the other 11 (and the other 11 eat at an identical pace). You have 4 cakes (which the rats do want to eat). You can put as many rats on a cake as you want at a time, and you can use as many cakes at a time as you…
- 05
Find Faster Rat (Puzzle - 16 Rats)
The puzzle remains the same, but you are given 16 rats instead of 12.
- 06
Max Rats for Faster Rat Puzzle (4 Cakes)
Determine the maximum number of rats from which we can find the faster rat using 4 cakes.
- 07
Stack vs Heap Memory
Explain the difference between Stack memory and Heap memory.
- 08
What is Inheritance?
Explain what inheritance is.
- 09
Virtual Function and Class in C++
Explain what a virtual function and virtual class in C++ are, along with their applications.
- 10
Deadlock (OS)
Explain what deadlock is, the conditions required for deadlock, and a general scenario where deadlock may occur.
- 11
Cab Management System Design
Design and implement a cab management system, focusing on design principles and modular coding. This involved an hour-long discussion on the design and implementation aspects.
PhonePe interview questions FAQ
What questions are asked in PhonePe interviews?
Candidates reported 169 distinct questions across 40 PhonePe interviews. 110 coding and DSA questions, 38 system design questions, 10 behavioural and HR questions, 11 other questions.
Which PhonePe interview questions are asked most often?
The most repeated are "Burst Balloons" (4 times), "Kth Smallest Element in a Sorted Matrix" (3 times), "Remove K Digits" (3 times), "Design Instagram" (3 times), "Min Stack" (2 times).
How difficult are PhonePe interview questions?
Of the questions candidates rated, 2% were easy, 51% medium and 47% hard.