ByteDance Front end Engineer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Medium

It started with an informal talk after he gave his introduction. We talked about the cyclone that was going to be there and what I did in my internship and my previous projects. Then we moved to questions. After solving both questions he asked if I had questions.

Q1. 
Kth Largest Element Problem Statement
Given an array of distinct positive integers and a number 'K', your task is to find the K'th largest element in the array.
Example:
Input:
Array: [2,1,5,6,3,8], K ...read more
Ans. 
Find the Kth largest element in an array of distinct positive integers.
• Sort the array in non-increasing order

• Return the Kth element from the sorted array

• Handle multiple test cases
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Q2. 
Orange Rotting Problem Statement
Consider a grid containing oranges. Each cell in this grid can hold one of three integer values:
• Value 0: Represents an empty cell.
• Value 1: Represents a fresh orang...read more
Ans. 
The task is to determine the minimum time required for all fresh oranges to become rotten in a grid.
• Create a queue to store the rotten oranges and their time of rotting.

• Iterate through the grid to find the initial rotten oranges and add them to the queue.

• Perform BFS by popping each rotten orange from the queue, rot adjacent fresh oranges, and add them to the queue with updated time.

• Continue until the queue is empty, ke...read more
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Round duration - 45 minutes
Round difficulty - Easy

This was a design round.

Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Find the k-th Node from the End of a Linked List
Given the head node of a singly linked list and an integer 'k', this problem requires you to determine the value at the k-th node from the end of the linke...read more
Ans. 
To find the k-th node from the end of a linked list, iterate through the list to determine the size, then traverse again to reach the k-th node from the end.
• Iterate through the linked list to determine its size.

• Calculate the position of the k-th node from the end based on the size of the list.

• Traverse the list again to reach the k-th node from the end.

• Return a pointer to the k-th node from the end.
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Round duration - 60 Minutes
Round difficulty - Easy

High level System Design

Q1. Can you design a system like Uber, explaining the various components and architecture involved?
Ans. 
Designing a system like Uber involves components like user app, driver app, server, database, and algorithms for matching and routing.
• User app for booking rides and tracking

• Driver app for accepting rides and navigation

• Server for handling requests and communication between apps

• Database for storing user, driver, and ride information

• Algorithms for matching riders with drivers and routing
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Round duration - 45 minutes
Round difficulty - Easy

Basic HR questions

Round duration - 120 minutes
Round difficulty - Easy

It was a mix of mathematical aptitude, logical ability, and puzzles along with 2 programming questions of easy and medium levels. Time was enough and no sectional time was present. 1-2 MCQs on SQL was also present.

Q1. 
Boolean Matrix Transformation Challenge
Given a 2-dimensional boolean matrix mat of size N x M, your task is to modify the matrix such that if any element is 1, set its entire row and column to 1. Specifi...read more
Ans. 
Modify a boolean matrix such that if any element is 1, set its entire row and column to 1.
• Iterate through the matrix to find elements with value 1

• Store the row and column indices of these elements

• Update the entire row and column for each element found to be 1
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Round duration - 60 minutes
Round difficulty - Easy

It was an online video interview round on HackerEarth with a simultaneous code option. It was mostly justifying your resume in the first 15 minutes. After that OOPS was majorly asked. Basics of programming including questions on STL were asked. A class that required inheritance was asked by the interviewer to write. I was helped by the interviewer if I got stuck somewhere, Some questions on the implementation of hashmaps and priority queues were also asked. A puzzle was asked which luckily struct to me at that moment.

Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
0/1 Knapsack Problem Statement
A thief is planning to rob a store and can carry a maximum weight of 'W' in his knapsack. The store contains 'N' items where the ith item has a weight of 'wi' and a value of...read more
Ans. 
Yes, the 0/1 Knapsack problem can be solved using dynamic programming with a space complexity of not more than O(W).
• Use a 1D array to store the maximum value that can be stolen for each weight capacity from 0 to W.

• Iterate through each item and update the array based on whether including the item would increase the total value.

• The final value in the array at index W will be the maximum value that can be stolen.
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Q2. 
Find the Second Largest Element
Given an array or list of integers 'ARR', identify the second largest element in 'ARR'.
If a second largest element does not exist, return -1.
Example:
Input:
ARR = [2,...read more
Ans. 
Find the second largest element in an array of integers.
• Iterate through the array to find the largest and second largest elements.

• Handle cases where all elements are identical.

• Return -1 if a second largest element does not exist.
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Round duration - 60 Minutes
Round difficulty - Easy

System Design Round

Q1. Design a system for Twitter, discussing its architecture, key components, and scalability considerations.
Ans. 
Design a scalable system for Twitter with key components and architecture.
• Use microservices architecture for scalability and fault isolation.

• Key components include user service, tweet service, timeline service, and notification service.

• Use a distributed database like Cassandra for storing tweets and user data.

• Implement a message queue like Kafka for handling real-time updates and notifications.

• Use a caching layer like ...read more
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Round duration - 30 Minutes
Round difficulty - Easy

It is just a formality

Round duration - 60 minutes
Round difficulty - Easy

The round consisted of 2 coding Problems and it lasted for 60 minutes from 12:00 PM to 1:00 PM on Hackerearth.
Use of other IDEs was prohibited and video was on.

Q1. 
Implement indexOf Function
You are provided with two strings A and B. Your task is to find the index of the first occurrence of A within B. If A is not found in B, return -1.
Example:
Input:
A = "bc", ...read more
Ans. 
Implement a function to find the index of the first occurrence of one string within another string.
• Iterate through the second string and check if a substring of the same length as the first string matches the first string.

• Return the index of the first occurrence of the first string within the second string, or -1 if not found.

• Handle edge cases like empty strings or when the first string is longer than the second string
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Q2. 
Problem: Search In Rotated Sorted Array
Given a sorted array that has been rotated clockwise by an unknown amount, you need to answer Q queries. Each query is represented by an integer Q[i], and you must ...read more
Ans. 
Search for integers in a rotated sorted array efficiently.
• Implement binary search to find the target integer in the rotated array.

• Handle the rotation by checking which side of the array is sorted before performing binary search.

• Return the index of the target integer if found, else return -1.

• Time complexity of O(logN) is required for each query.
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Round duration - 60 minutes
Round difficulty - Medium

The round was conducted on Google Meet with 2 interviewers . They were friendly and helpful.
The timing was 12:00 to 1:00 PM.
Our Video was on .

Q1. 
Distinct Subsequences Problem Statement
You are given a string 'S' of length 'N' which may include duplicate alphabets. Your goal is to calculate the number of distinct subsequences in the string.
Exampl...read more
Ans. 
Calculate the number of distinct subsequences in a string with possible duplicates.
• Use dynamic programming to keep track of the count of distinct subsequences for each character in the string.

• Consider the cases where the current character is included or excluded in the subsequence.

• Handle duplicates by considering the previous occurrence of the character.

• Return the count of distinct subsequences modulo 10^9 + 7.
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Round duration - 60 minutes
Round difficulty - Easy

This was a Behavioral Round. It lasted for 45-50 minutes. It consisted of a discussion on my projects. The interviewer was very impressed by the way I explained my projects. She even appreciated me for that. This was followed by normal HR questions .Timing of This round was 4:00 PM to 5:00 PM

It was a coding round where i need to solve 3 DSA Questions in 1.5 hour

Q1. This is Technical round where i was asked to implement the Two Question of Dsa one is bases on greedy and another is dp , another one is leetcode hard (finding maxaimal area of rectangle in matrix of 1 and...read more
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Q2. Greedy Q was direct i don't remember clearly. I was selected for the 2nd round
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Q1. It was also a technical round but bases on LLD problem statement. I was given a problem statement to design a society security system and the they need psudo code for complete implementation using correct ...read more
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Q1. I was not selected for 4th round but heard that there were Q on cs fundamentals.
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In test I had to solve 3 dsa questions in 1 hour

Q1. I have asked 2 DSA questions in my interview
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