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
Answered by AI
Add your answer
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
Answered by AI
Add your answer

Round duration - 45 minutes
Round difficulty - Easy

This was a design round.

Round duration - 90 minutes
Round difficulty - Medium

Q1. 
Rotate Matrix Right K Times
You are given a matrix MAT of size 'N' * 'M', where 'N' is the number of rows and 'M' is the number of columns, along with a positive integer 'K'. Your task is to rotate the ma...read more
Ans. 
Rotate a matrix to the right 'K' times by shifting each column to the right 'K' times.
• Iterate 'K' times to perform right rotation on the matrix

• Shift each column to the right by one position in each rotation

• Handle wrapping around the matrix when shifting columns

• Return the matrix elements row-wise after 'K' rotations
Answered by AI
Add your answer
Q2. 
Word Search Problem Statement
Given a two-dimensional grid of size N x M consisting of upper case characters and a string 'WORD', determine how many times the 'WORD' appears in the grid.
The 'WORD' can b...read more
Ans. 
Count how many times a given word appears in a 2D grid by moving in any of the eight possible directions.
• Iterate through each cell in the grid and check if the word can be formed starting from that cell in any of the eight directions.

• Use recursion to explore all possible paths from a starting cell to form the word.

• Keep track of visited cells to avoid revisiting the same cell in the same path.

• Return the count of how man...read more
Answered by AI
Add your answer

Round duration - 75 minutes
Round difficulty - Medium

Interview started with an introduction and walk through the resume for first 5 minutes. After that, interview asked few coding questions.

Q1. 
Problem Statement: Largest Island
You are provided with a non-empty grid consisting of only 0s and 1s. Your task is to determine the maximum area of an island within the given grid.
An island consists of a...read more
Ans. 
Find the maximum area of an island in a grid of 0s and 1s.
• Iterate through the grid and perform depth-first search (DFS) to find connected 1s.

• Keep track of the area of each island found and return the maximum area.

• Consider all four directions (horizontal, vertical, and diagonal) while exploring the island.

• Handle edge cases like grid boundaries and already visited cells during DFS.

• If no island is present, return 0 as the...read more
Answered by AI
Add your answer
Q2. 
Pythagorean Triplet Problem
Determine if there exists a Pythagorean triplet within a given array of integers. A Pythagorean triplet consists of three numbers, x, y, and z, such that x^2 + y^2 = z^2.
Expl...read more
Ans. 
Check if there exists a Pythagorean triplet in a given array of integers.
• Iterate through all possible triplets in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations of three numbers from the array.

• Check if the sum of squares of two numbers is equal to the square of the third number.
Answered by AI
Add your answer
Q3. 
Top View of Binary Tree Problem Statement
Given a Binary Tree of integers, you are tasked with finding the top view of the binary tree. The top view is the set of nodes visible when the tree is viewed fro...read more
Ans. 
Find the top view of a Binary Tree by returning a list of visible nodes when viewed from the top.
• Traverse the Binary Tree in level order and keep track of the horizontal distance of each node from the root.

• Use a map to store the nodes at each horizontal distance, and only keep the topmost node for each horizontal distance.

• Return the values of the topmost nodes in the map as the top view of the Binary Tree.
Answered by AI
Add your answer

Round duration - 90 minutes
Round difficulty - Medium

This round was focused on DSA along with short discussion on computer science fundamentals. For coding problems, I was asked to code the first problem only. For others, had to discuss the approach only. For computer science fundamentals, discussion on OOPS. Differences between process and threads were discussed.

Q1. 
Fixing a Swapped Binary Search Tree
Given a Binary Search Tree (BST) where two nodes have been swapped by mistake, your task is to restore or fix the BST without changing its structure.
Input:
The first...read more
Ans. 
Restore a Binary Search Tree by fixing two swapped nodes without changing its structure.
• Identify the two nodes that are swapped by mistake in the BST.

• Swap the values of the two identified nodes to restore the BST.

• Perform an in-order traversal of the BST to verify the correct restoration.

• Ensure no extra space other than the recursion stack is used for the solution.
Answered by AI
Add your answer
Q2. 
Implement Stack with Linked List
Your task is to implement a Stack data structure using a Singly Linked List.
Explanation:
Create a class named Stack which supports the following operations, each in O(1...read more
Ans. 
Implement a Stack data structure using a Singly Linked List with operations like getSize, isEmpty, push, pop, and getTop in O(1) time.
• Create a class named Stack with methods for getSize, isEmpty, push, pop, and getTop.

• Use a Singly Linked List to store the elements of the stack.

• Ensure that each operation runs in constant time O(1).

• Handle edge cases like empty stack appropriately.

• Test the implementation with sample queri...read more
Answered by AI
Add your answer

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
Answered by AI
Add your answer

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.
Answered by AI
Add your answer
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.
Answered by AI
Add your answer

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
Answered by AI
Add your answer

Round duration - 30 Minutes
Round difficulty - Easy

It is just a formality

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.
Answered by AI
Add your answer

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
Answered by AI
Add your answer

Round duration - 45 minutes
Round difficulty - Easy

Basic HR questions

Round duration - 90 Minutes
Round difficulty - Hard

Timing was 11 am. Platform was quite well.

Q1. 
Rat in a Maze Problem Statement
You need to determine all possible paths for a rat starting at position (0, 0) in a square maze to reach its destination at (N-1, N-1). The maze is represented as an N*N ma...read more
Ans. 
Find all possible paths for a rat in a maze from source to destination.
• Use backtracking to explore all possible paths in the maze.

• Keep track of visited cells to avoid revisiting them.

• Explore all possible directions (up, down, left, right) from each cell.

• Add the current direction to the path and recursively explore further.

• When reaching the destination, add the path to the list of valid paths.
Answered by AI
Add your answer
Q2. 
Minimum Cost to Destination
You are given an NxM matrix consisting of '0's and '1's. A '1' signifies that the cell is accessible, whereas a '0' indicates that the cell is blocked. Your task is to compute ...read more
Ans. 
Find the minimum cost to reach a destination in a matrix with blocked cells.
• Use Breadth First Search (BFS) algorithm to explore all possible paths from the starting point to the destination.

• Keep track of the cost incurred at each cell and update it as you move through the matrix.

• Return the minimum cost to reach the destination or -1 if it is unreachable.

• Consider edge cases such as when the starting point is the destina...read more
Answered by AI
Add your answer

Round duration - 90 Minutes
Round difficulty - Medium

it was time bound coding test round. The questions were from array and string. There were 2 questions.

Q1. 
K-Palindrome Problem Statement
Determine whether a given string str can be considered a K-Palindrome.
A string is considered a K-Palindrome if it can be transformed into a palindrome after removing up to...read more
Ans. 
The problem is to determine whether a given string can be considered a K-Palindrome by removing up to 'k' characters.
• Iterate through the string from both ends and check if characters match, if not increment removal count

• If removal count is less than or equal to k, return True, else return False

• Use dynamic programming to optimize the solution by storing subproblem results
Answered by AI
Add your answer

Round duration - 30 Minutes
Round difficulty - Easy

in this round manager spoke to me and explained about project and joining date later hr spoke to me regarding on boarding process