BigBasket Software Developer Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Easy

This round was held during university hours and consisted of 2 coding questions.

Round duration - 120 minutes
Round difficulty - Easy

Make sure you do no cutting and are clear about the approach you'd be following. 
 

Q1. What is the running median of an input stream?
Ans. 
Running median of an input stream is the median value of the numbers seen so far in a continuous stream of data.
• Maintain two heaps - a max heap for the lower half of the numbers and a min heap for the upper half.

• Keep the number of elements in the two heaps balanced or differ by at most 1.

• If the total number of elements is odd, the median is the root of the max heap. If even, it is the average of the roots of the two he...read more
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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
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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
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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
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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.
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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.
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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.
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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
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Round duration - 75 minutes
Round difficulty - Easy

This was the online round held at university. All students who met the eligibility criteria were called for the online test on hackerrank.

Q1. 
Anagram Difference Problem Statement
Given two strings, 'STR1' and 'STR2', of equal lengths, determine the minimum number of manipulations required to make the two strings anagrams of each other.
Input:
...read more
Ans. 
The problem involves finding the minimum number of manipulations required to make two strings anagrams of each other.
• Create frequency maps for both strings

• Find the absolute difference in frequencies of each character

• Sum up the absolute differences to get the total manipulations needed
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Round duration - 90 Minutes
Round difficulty - Medium

This round was technical round and the interview started with formal introduction and general questions.
After that We had a discussion on LRU Cache.
Followed by coding and set of data structure questions.

Q1. 
Gas Tank Problem Statement
You have a car with a gas tank of infinite capacity. There are 'N' gas stations located along a circular route, numbered from 0 to N-1. You begin your journey with an empty tank...read more
Ans. 
Find the starting gas station index to complete a circular route with gas and cost arrays.
• Iterate through gas stations, keeping track of total gas and total cost from each station

• If total gas is greater than or equal to total cost, update the starting station index

• Return the starting station index if a valid one is found, else return -1
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Round duration - 90 minutes
Round difficulty - Medium

This Round was DS and Algo round and it started with formal introduction, followed by 2 problems. We first dicussed the approach the time complexity and proper code covering all cases.

Q1. 
Boundary Traversal of Binary Tree
Given a binary tree of integers, your task is to print the boundary nodes of this binary tree in an anti-clockwise direction starting from the root node.
Input:
The fir...read more
Ans. 
Print the boundary nodes of a binary tree in an anti-clockwise direction starting from the root node.
• Traverse the left boundary nodes from the root to the leftmost leaf node.

• Traverse the leaf nodes from left to right.

• Traverse the right boundary nodes from the rightmost leaf node to the root.
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Q2. 
Maximum Sum of Two Non-Overlapping Subarrays
Given an integer array ARR and a positive integer K, your objective is to find two non-overlapping subarrays (contiguous) of length K each, such that their sum...read more
Ans. 
Find two non-overlapping subarrays of length K with maximum sum in an integer array.
• Iterate through the array to find all possible subarrays of length K.

• Calculate the sum of each pair of non-overlapping subarrays of length K.

• Keep track of the maximum sum obtained from the pairs of subarrays.
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Round duration - 30 minutes
Round difficulty - Easy

This was the Final Interview and it started with formal introduction and general HR questions. Then We discussed about the projects and the things written in my resume. The interviewer was very frank and this round was very interactive. He asked me about my college, my future plans, teachers, various subjects, why Expedia and questions like that.

Round duration - 120 minutes
Round difficulty - Easy

The test was divided into two parts : Section A had questions from Quantitative, C language, Logical and English. The second part had two coding questions.

Q1. 
Deletion in Circular Linked List Problem Statement
Given a Circular Singly Linked List of integers, and a specific value 'VAL', your task is to delete the first occurrence of this value in the linked list...read more
Ans. 
Delete the first occurrence of a specific value in a Circular Linked List.
• Traverse the circular linked list to find the value to be deleted.

• Update the pointers to skip the node containing the value.

• Handle edge cases like deleting the only node in the list.

• Return the modified circular linked list.
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Q2. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraints.
• Use a combination of a doubly linked list and a hashmap to efficiently implement the LRU cache.

• Keep track of the least recently used item and update it accordingly when new items are added.

• Ensure that the cache does not exceed its capacity by evicting the least recently used item when necessary.
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Round duration - 120 minutes
Round difficulty - Easy

Hello everyone! Expedia came to our campus for full time hiring of final year students. They had shortlisted candidates for the interviews by taking an online test comprised of four sections (Quantitative, C, Logical and English). Every section had a timer attached to it, so you need to think and answer quickly. Although, the questions were easy but cutoff was quite high. This round was followed by a coding round, comprised of two questions.

Q1. 
Problem: Deletion in Circular Linked List
You are provided with a Circular Linked List of integers and a specific integer, referred to as 'key'.
Your task is to implement a function that locates the spec...read more
Ans. 
Implement a function to delete a specific key from a Circular Linked List of integers.
• Traverse the Circular Linked List to find the key to be deleted.

• Adjust the pointers to remove the node containing the key.

• Handle the case where the Circular Linked List becomes empty after deletion.

• Return -1 if the Circular Linked List is empty after deletion.
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Q2. 
Page Faults Identification Problem Statement
In computing, a page fault occurs when a process accesses a memory page that is not currently mapped by the memory management unit. To handle new pages being b...read more
Ans. 
The problem involves determining the number of page faults using the Least Recently Used (LRU) replacement algorithm.
• Page faults occur when a process accesses a memory page not currently mapped by the memory management unit.

• Page replacement algorithm like LRU is used to decide which existing page should be replaced.

• The goal is to calculate the number of page faults based on the given input sequences and memory capacity...read more
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Round duration - 60 minutes
Round difficulty - Easy

The man who was taking my first round was my alumni. He started-off by asking my introduction and then gave me 2 programming questions to code. He then navigated on to my Codechef profile and asked a question that I did in the June 14 Long Contest. I explained him and he was satisfied. 
Tips : You don’t have to answer the stuffs quickly, rather you need to develop some test cases and have some discussion regarding the structure of the problem, and then answer.

Q1. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, it indicates the presence of a cycle in the linked list.

• Use Floyd's Cycle Detection Algorithm for efficient detection of cycles in a linked list.
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Q2. 
Closest Sum Problem Statement
Given an array of integers ARR of size N and an integer target, find three integers in ARR such that their sum is closest to the target. If there are two closest sums, return...read more
Ans. 
Find three integers in an array whose sum is closest to a given target, return the smallest sum if there are two closest sums.
• Iterate through all possible triplets in the array to find the sum closest to the target.

• Keep track of the closest sum found so far and update it if a closer sum is found.

• Return the closest sum at the end of the iteration.
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