Tokopedia Software Engineer Intern Interview Questions and Answers

Round duration - 45 Minutes
Round difficulty - Medium

It was in the mid day and since I applied for a Frontend role the discussion was majorly around data structure and bit of Javascript.
The interviewer was helping and good listener.

Q1. 
Merge Two Sorted Linked Lists Problem Statement
You are provided with two sorted linked lists. Your task is to merge them into a single sorted linked list and return the head of the combined linked list.
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Ans. 
Merge two sorted linked lists into a single sorted linked list without using additional space.
• Create a dummy node to start the merged list

• Compare the values of the two linked lists and add the smaller value to the merged list

• Move the pointer of the merged list and the pointer of the smaller value list

• Continue this process until one of the lists is fully traversed

• Append the remaining elements of the other list to the me
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Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. 
Sort an array of 0s, 1s, and 2s in linear time complexity.
• Use three pointers to keep track of 0s, 1s, and 2s while traversing the array.

• Swap elements based on the values encountered to sort the array in-place.

• Time complexity should be O(N) and space complexity should be O(1).
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Round duration - 60 Minutes
Round difficulty - Medium

It was more of a in depth round on the framework I'm working on and problem solving.

Q1. What is the event loop and what is its significance?
Ans. 
The event loop is a mechanism in programming that allows for asynchronous execution of code.
• The event loop is a key component in JavaScript's runtime environment, responsible for handling asynchronous operations.

• It continuously checks the call stack for any pending tasks and executes them in a non-blocking manner.

• The event loop ensures that the program remains responsive by allowing other code to run while waiting for ...read more
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Q2. Can you provide examples of output-based questions in JavaScript that utilize browser APIs?
Ans. 
Output-based questions in JavaScript using browser APIs
• Example 1: Write a script that uses the Geolocation API to display the user's current location on a map

• Example 2: Create a program that uses the Web Audio API to play a sound when a button is clicked

• Example 3: Develop a web page that uses the Canvas API to draw a simple animation
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Q3. How would you design a system to support localization in a mobile app?
Ans. 
Designing a system to support localization in a mobile app
• Use resource files to store localized strings for different languages

• Implement a language selection feature for users to choose their preferred language

• Utilize localization libraries or frameworks to streamline the process

• Consider cultural differences when localizing content, such as date formats and currency symbols
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Round duration - 75 Minutes
Round difficulty - Hard

It was more of a fitment/managerial round.
Didn't had any coding questions, but was asked more on approaches and optimisations.
Discussions on the project you have worked on.

Q1. You need to find the fastest 3 horses out of a group, given that you can only race 5 horses at a time. How would you approach this problem?
Ans. 
To find the fastest 3 horses out of a group with 5 horses racing at a time, we can use a tournament style approach.
• Divide the horses into groups of 5 and race them against each other. This will give you the fastest horse in each group.

• Take the winners from each group and race them against each other. The top 3 horses in this final race will be the fastest 3 overall.

• Keep track of the results and compare the timings to d
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Q2. How do you debug the root cause of lag on a screen?
Ans. 
To debug lag on a screen, analyze code, check for memory leaks, optimize rendering, and use profiling tools.
• Analyze code to identify any inefficient algorithms or operations causing lag.

• Check for memory leaks that could be impacting performance.

• Optimize rendering by reducing the number of draw calls, optimizing shaders, and minimizing overdraw.

• Use profiling tools like Xcode Instruments or Android Profiler to identify p
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Q3. Can you explain the architecture of the app you have recently worked on?
Ans. 
The app I recently worked on is a social media platform for sharing photos and connecting with friends.
• The app follows a client-server architecture, with the client being the mobile app and the server handling data storage and processing.

• The client side is built using React Native for cross-platform compatibility.

• The server side is implemented using Node.js with a MongoDB database for storing user data and photos.

• The a...read more
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Q1. By when can u join, hr told me they shared my resume with multiple managers and waiting for it to be shortlisted
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Q1. Acid, SQL vs nosql, react based, asynchronous working of js, event loop, etc. How will u design a matrimony site such that search query will contain multiple preferences - age, height, income, etc (say 100...read more
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Q2. How to implement any one of acid property.
Ans. 
To implement ACID property, use transactions to ensure atomicity, consistency, isolation, and durability of data.
• Use transactions to group related database operations together.

• Ensure that all operations within a transaction are completed successfully or none of them are.

• Maintain consistency by enforcing data integrity constraints.

• Isolate transactions to prevent interference from other transactions.

• Ensure durability by ...read more
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Q1. Js output questions. A recursion based coding problem. (Easy-medium)
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Q2. Was asked to develop an ui but i told the interviewer I'm more into backend so she asked me some backend questions after this. Didn't have to solve the ui task.
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Q3. I answered almost all questions.
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Q1. Impliment counter using closure in js
Ans. 
Implement a counter using closure in JavaScript.
• Create a function that returns another function which increments a counter variable.

• The counter variable should be defined in the outer function's scope and only accessible to the inner function.

• Each time the inner function is called, increment the counter variable and return its value.
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Q2. Explain promises, promise.all(), impliment binary search
Ans. 
Promises are objects representing the eventual completion or failure of an asynchronous operation. promise.all() is a method that takes an array of promises and returns a single promise that resolves when all of the promises have resolved.
• Promises are used in JavaScript to handle asynchronous operations.

• promise.all() takes an array of promises and returns a single promise that resolves when all promises in the array ha...read more
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Q1. Questions on kafka, cache invalidation, diff b/w authentication and authorization
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Q1. Basic questions on what you have mentioned in resume , design patterns , reactjs questions , explain your project
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Some database questions,some java questions .

Q1. What is the difference between javascript and jQuery.
Ans. 
JavaScript is a programming language used for web development, while jQuery is a library built with JavaScript to simplify HTML document traversal and manipulation.
• JavaScript is a programming language, while jQuery is a library written in JavaScript.

• JavaScript can be used for a wide range of tasks, while jQuery is mainly used for DOM manipulation and event handling.

• JavaScript is a core technology for web development, w...read more
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Q2. Define different types of join
Ans. 
Different types of joins are used in SQL to combine rows from two or more tables based on a related column between them.
• Inner Join: Returns rows when there is at least one match in both tables.

• Left Join (or Left Outer Join): Returns all rows from the left table and the matched rows from the right table.

• Right Join (or Right Outer Join): Returns all rows from the right table and the matched rows from the left table.

• Full ...read more
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Q3. Define multithreading concept and exception handling.
Ans. 
Multithreading allows multiple threads to run concurrently, while exception handling deals with errors in a program.
• Multithreading involves running multiple threads simultaneously to improve performance and responsiveness.

• Threads share the same memory space but have their own program counter and registers.

• Exception handling is a mechanism to handle errors or exceptional situations in a program.

• It helps prevent the prog...read more
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Round duration - 75 minutes
Round difficulty - Medium

Test Comprises of 3 coding questions and some MCQs

Round duration - 60 minutes
Round difficulty - Medium

2 coding questions of (1 easy and 1 medium level) on hackerrank code-pair with the Interviewer

Round duration - 60 minutes
Round difficulty - Easy

This Round was based on CS fundamentals and One coding question was there as a Code-pair.

Q1. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
Find the Next Greater Element for each element in a list of integers.
• Iterate through the list of integers from right to left.

• Use a stack to keep track of elements whose NGE is yet to be found.

• Pop elements from the stack until a greater element is found or the stack is empty.

• Assign the NGE as the top element of the stack or -1 if the stack is empty.
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Data Structures and Algorithms questions were asked

Q1. Java Questions were asked
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Round duration - 90 minutes
Round difficulty - Medium

Total of 8 questions:

4 MCQ(oops and expected output type questions) + other 2 were coding questions, out of which one is some class implementation question.

Q1. 
Count Subarrays with Sum Divisible by K
Given an array ARR and an integer K, your task is to count all subarrays whose sum is divisible by the given integer K.
Input:
The first line of input contains an...read more
Ans. 
Count subarrays with sum divisible by K in an array.
• Iterate through the array and keep track of the running sum modulo K.

• Use a hashmap to store the frequency of remainders.

• For each prefix sum, check how many previous prefix sums have the same remainder.

• Return the total count of subarrays with sum divisible by K.
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Round duration - 60 minutes
Round difficulty - Easy

This round was with the USA team, the panel consisted of 2 members. It took place at around 9 PM IST. The interviewer's focus was on approach.

Q1. 
Sort an Array in Wave Form
You are given an unsorted array ARR. Your task is to sort it so that it forms a wave-like array.
Input:
The first line contains an integer 'T', the number of test cases.
For ea...read more
Ans. 
Sort an array in a wave-like pattern where each element is greater than or equal to its adjacent elements.
• Iterate through the array and swap elements at even indices with their adjacent odd indices to form a wave pattern.

• There can be multiple valid wave arrays, so any valid wave array is acceptable.

• Ensure the first element is greater than or equal to the second element to start the wave pattern.
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Q2. 
Convert a Number to Words
Given an integer number num, your task is to convert 'num' into its corresponding word representation.
Input:
The first line of input contains an integer ‘T’ denoting the number o...read more
Ans. 
Convert a given integer number into its corresponding word representation.
• Implement a function that takes an integer as input and returns the word representation of that number.

• Break down the number into its individual digits and convert each digit into its word form.

• Handle special cases like numbers between 10 and 19, and multiples of 10.

• Combine the word forms of individual digits to form the final word representation
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Round duration - 40 minutes
Round difficulty - Easy

It was a managerial round. The position of the person taking the interview was of a technical architect. As was informed by the recruiter, previously he was a technical architect at Amazon.

Q1. How does Facebook store comments in its database?
Ans. 
Facebook stores comments in its database using a combination of relational and non-relational databases.
• Comments are typically stored in a relational database like MySQL for structured data storage.

• For scalability and performance, Facebook may also use a NoSQL database like Cassandra or HBase for storing comments in a denormalized format.

• Metadata related to comments such as likes, timestamps, and user information may b...read more
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