Quikr Lead Software Consultant Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

It comprised of general aptitude questions and two coding questions. It was an offline test.

Q1. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. 
The N Queens Problem involves finding all possible placements of N queens on an N x N chessboard where no two queens threaten each other.
• Use backtracking algorithm to explore all possible configurations.

• Keep track of rows, columns, and diagonals to ensure queens do not attack each other.

• Generate and print valid configurations where queens are placed safely.

• Consider constraints and time limit for efficient solution.

• Exam...read more
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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 integer array containing only 0s, 1s, and 2s in linear time complexity.
• Use three pointers to keep track of the positions of 0s, 1s, and 2s in the array.

• Iterate through the array and swap elements based on the values encountered.

• Achieve sorting in a single scan over the array without using any extra space.
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Round duration - 60 minutes
Round difficulty - Easy

After having a technical discussion about my CV. He gave me two questions to code.

Q1. 
Ninja and Substrings Problem Statement
Ninja has to determine all the distinct substrings of size two that can be formed from a given string 'STR' comprising only lowercase alphabetic characters. These su...read more
Ans. 
Find all unique contiguous substrings of size two from a given string.
• Iterate through the string and extract substrings of size two

• Use a set to store unique substrings

• Return the set as an array of strings
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Q2. 
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, there is a cycle in the linked list.

• If one of the pointers reaches the end of the list (null), there is no cycle.
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Round duration - 30 minutes
Round difficulty - Easy

This was supposed to be the HR round but out of surprise the interviewer started by giving me a question to code. 
After I approached this question with the right solution he just asked about my family. After that he said to wait. After half an hour the results were announced. A total of three students were hired and I was amongst one of them.

Q1. 
Balanced Parentheses Combinations
Given an integer N representing the number of pairs of parentheses, find all the possible combinations of balanced parentheses using the given number of pairs.
Explanati...read more
Ans. 
Generate all possible combinations of balanced parentheses for a given number of pairs.
• Use recursion to generate all possible combinations of balanced parentheses.

• Keep track of the number of open and close parentheses used in each combination.

• Return the valid combinations as an array of strings.
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2 questions in 60 minutes

Q1. System design, 1 hr
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Q2. Don’t remember the question
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Q1. Asked about my school life
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Q2. Asked about my family
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Q1. What is thread ?
Ans. 
A thread is a lightweight process that can run concurrently with other threads within the same process.
• Threads allow for parallel execution of tasks within a single process.

• Threads share the same memory space and resources of the process they belong to.

• Threads can communicate with each other through shared memory or message passing.

• Examples: Java threads, POSIX threads (pthreads) in C/C++.
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Q2. Inter process communication and project?
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Q1. Stock buy and sell with at most 2 transaction
Ans. 
Implement a solution to find the maximum profit from buying and selling stocks with at most 2 transactions.
• Use dynamic programming to keep track of maximum profit at each day with 0, 1, or 2 transactions.

• Consider the possibility of splitting the transactions into two separate parts.

• Calculate the maximum profit by iterating through the prices array and updating the maximum profit accordingly.
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Q2. Binary search to find target
Ans. 
Binary search is a divide and conquer algorithm that efficiently finds a target value in a sorted array.
• Divide the array in half and compare the target value with the middle element

• If the target is less than the middle element, search the left half. If greater, search the right half

• Repeat the process until the target is found or the subarray is empty
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Q1. General about project
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Q2. Design paytm wallet
Ans. 
Design a digital wallet system similar to Paytm.
• Allow users to add money to their wallet using various payment methods like credit/debit cards, net banking, UPI, etc.

• Enable users to make payments for various services like mobile recharge, bill payments, online shopping, etc.

• Implement security measures like two-factor authentication, encryption of sensitive data, and regular security audits.

• Provide features like transac...read more
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Round duration - 90 minutes
Round difficulty - Medium

The test was conducted in the evening from 5:00 pm to 6:30 pm. Because of the covid situation, all the students attempted the test from their homes. But it was a webcam-based test to avoid any kind of cheating.
There were 3 coding problems to be done in 90 minutes.
After resume based shortlisting, 70 candidates were selected to appear for the test out of which 30 were shortlisted for interviews.

Q1. 
Amazing Strings Problem Statement
Determine if the third string contains all the characters from both the first and second strings in any order. If so, return "YES"; otherwise, return "NO".
Input:
Line ...read more
Ans. 
Check if the third string contains all characters from the first and second strings in any order.
• Create a frequency map for characters in the first and second strings.

• Check if all characters in the third string are present in the frequency map.

• Ensure the count of characters in the third string matches the count in the frequency map.

• Return 'YES' if all conditions are met, otherwise return 'NO'.
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Q2. 
Shortest Path Visiting All Nodes
You are given a connected undirected unweighted graph comprising 'N' nodes and 'M' edges. In this graph, each pair of connected nodes is linked by exactly one undirected e...read more
Ans. 
Find the length of the shortest path visiting all nodes in a connected undirected unweighted graph.
• Use Breadth First Search (BFS) to find the shortest path that visits all nodes at least once.

• Maintain a bitmask to keep track of visited nodes and their states.

• Consider all possible permutations of nodes to find the shortest path length.
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Q3. 
Meeting Rooms Allocation Problem Statement
Stark Industry is planning to organize meetings for various departments in preparation for Stark Expo. Due to limited rooms in Stark Tower, the goal is to alloca...read more
Ans. 
Determine the minimum number of conference rooms required for scheduling meetings.
• Sort the meetings by start time.

• Iterate through the meetings and keep track of rooms needed based on overlapping times.

• Use a priority queue to efficiently allocate rooms.

• Example: For meetings (1pm-4pm), (3pm-5pm), (4pm-6pm), 2 rooms are required.

• Ensure linear time complexity by optimizing the room allocation process.
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Round duration - 50 minutes
Round difficulty - Medium

This round started at 9 am and went till 4 pm.
Out of 70 students that appeared in online coding test, 30 were shortlisted for the first round (this round) of interviews.
In this round, everyone was asked one moderate level coding question. The interviewer provided the link to an IDE, where I wrote my code.
The interview started with the introduction being followed by 1 coding problem. In the end, the interviewer asked me if I wanted to ask any questions. To which I asked him my feedback so that I can improve my wear areas.
Of the 30 candidates, 17 were selected for the final interview round.

Q1. 
Print All Subsets Challenge
Given an array arr containing 'N' distinct integers, your task is to generate all possible non-empty subsets of this array.
Note: While the elements within each subset should ...read more
Ans. 
Generate all possible non-empty subsets of an array of distinct integers.
• Use recursion to generate all subsets by including or excluding each element in the array.

• Maintain a current subset and add it to the result when reaching the end of the array.

• Ensure elements within each subset are in increasing order.

• Handle the input and output format as specified in the question.
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Round duration - 50 minutes
Round difficulty - Easy

This was a technical + HR round. Started in the evening at 4:30 pm, this round went till 9:30 pm.
17 students were shortlisted for this final round of interview.
This interview was also virtual and involved both technical and HR-related questions. The interview started with an introduction and then questions based on my resume were asked.
Out of 17 candidates, 8 candidates got a full-time offer from Urban Company.

Q1. 
Find Row With Maximum 1's in a Sorted 2D Matrix
You are provided with a 2D matrix containing only the integers 0 or 1. The matrix has dimensions N x M, and each row is sorted in non-decreasing order. Your...read more
Ans. 
Find the row with the maximum number of 1's in a sorted 2D matrix.
• Iterate through each row of the matrix and count the number of 1's in each row.

• Keep track of the row index with the maximum number of 1's seen so far.

• Return the index of the row with the maximum number of 1's.

• If multiple rows have the same number of 1's, return the row with the smallest index.
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Round duration - 75 minutes
Round difficulty - Medium

The test had 3 questions which had to solved in 75 minutes.The test was of medium difficulty.

Q1. 
Meeting Rooms Allocation Problem Statement
Stark Industry is planning to organize meetings for various departments in preparation for Stark Expo. Due to limited rooms in Stark Tower, the goal is to alloca...read more
Ans. 
Determine the minimum number of conference rooms needed to schedule meetings without overlap.
• Sort the meetings by start time.

• Iterate through the meetings and keep track of the rooms in use.

• If a meeting starts after another ends, it can reuse the same room.

• If a meeting starts before another ends, a new room is needed.

• Return the maximum number of rooms in use at any point.
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Q2. 
Maximize XOR Value
You are provided with an integer X and are tasked with identifying an integer Y such that the bitwise XOR operation between X and Y yields the maximum possible value. The condition is t...read more
Ans. 
Find an integer Y such that XOR operation with X yields maximum value within given constraints.
• Iterate from the most significant bit to find the highest bit that can be toggled to maximize XOR value.

• To maximize XOR value, toggle the highest bit of X to 0 and all lower bits to 1.

• Ensure the final Y does not exceed (2^61) - 1.

• Example: For X = 3, the highest bit to toggle is at position 61, so Y = 2305843009213693950.

• Examp...read more
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Q3. 
Minimize Maximum Difference Between Adjacent Elements
You are provided with a non-decreasing array and an integer K. Your task is to remove exactly K elements from this array so that the maximum differenc...read more
Ans. 
Remove K elements from a non-decreasing array to minimize the maximum difference between adjacent elements.
• Sort the array in non-decreasing order.

• Iterate through the array and calculate the difference between adjacent elements.

• Remove elements to minimize the maximum difference.

• Return the minimized maximum difference.
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Round duration - 60 minutes
Round difficulty - Easy

The interview was taken by SDE2 and she was very friendly. All the questions asked were related to DS and algo. The first 10 minutes were used for introductions and the last 5 minutes were reserved for any questions that I have. Always try to ask meaningful questions at the end of the interview.

Q1. 
Frequency in a Sorted Array Problem Statement
Given a sorted array ARR and a number X, your task is to determine the count of occurrences of X within ARR.
Note:
• If X is not found in the array, return...read more
Ans. 
Count occurrences of a number in a sorted array efficiently.
• Use binary search to find the first and last occurrence of the target number in the array.

• Calculate the count of occurrences by subtracting the indices of the last and first occurrences.

• Handle cases where the target number is not found in the array.

• Time complexity: O(log(N)), Space complexity: O(1).
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Q2. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find the minimum time required to rot all fresh oranges in a grid.
• Use Breadth First Search (BFS) to simulate the rotting process

• Track the time taken to rot all oranges and return -1 if any fresh oranges remain

• Handle edge cases such as no fresh oranges or all oranges already rotten

• Consider using a queue to efficiently process neighboring oranges
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Q3. 
Clone Linked List with Random Pointer Problem Statement
Given a linked list where each node has two pointers: one pointing to the next node and another which can point randomly to any node in the list or ...read more
Ans. 
Yes, the cloning of a linked list with random pointer can be accomplished without utilizing extra space.
• Use a hashmap to store the mapping between original nodes and cloned nodes.

• Iterate through the original linked list to create the cloned linked list by mapping the random pointers using the hashmap.

• Time complexity of this approach is O(N) where N is the number of nodes in the linked list.
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Round duration - 60 minutes
Round difficulty - Medium

The focus of this round was mainly on my projects and internships. It was taken by a Senior SDE and it more of a technical interaction. I was asked in-depth about my projects and most of the questions asked around OS/DBMS were based on my projects.
The interviewer wanted to judge whether I have core knowledge about subjects like OS and DBMS and also about the projects that I had done.

Round duration - 60 minutes
Round difficulty - Easy

It was the culture fit round taken by the Director of Engineering.

Seat reservation system
bit manipulation
binary tree related

Q1. Bfs / dfs traversal question
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Round duration - 60 minutes
Round difficulty - Easy

Easy level DSA questions were asked to implement.

Q1. 
BFS Traversal in a Graph
Given an undirected and disconnected graph G(V, E) where V vertices are numbered from 0 to V-1, and E represents edges, your task is to output the BFS traversal starting from the ...read more
Ans. 
BFS traversal of an undirected and disconnected graph starting from vertex 0.
• Implement BFS algorithm to traverse the graph starting from vertex 0.

• Use a queue to keep track of visited nodes and their neighbors.

• Ensure the traversal starts from vertex 0 and follows the BFS order.

• Output the BFS traversal sequence for each test case in a separate line.

• Handle disconnected components by checking for unvisited nodes.

• Consider t...read more
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Q2. 
DFS Traversal Problem Statement
Given an undirected and disconnected graph G(V, E), where V is the number of vertices and E is the number of edges, the connections between vertices are provided in the 'GR...read more
Ans. 
DFS traversal problem to find connected components in an undirected and disconnected graph.
• Use Depth First Search (DFS) algorithm to traverse the graph and find connected components

• Maintain a visited array to keep track of visited vertices

• Iterate through all vertices and perform DFS on unvisited vertices to find connected components
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Q3. 
Nth Fibonacci Number Problem Statement
Calculate the Nth term in the Fibonacci sequence, where the sequence is defined as follows: F(n) = F(n-1) + F(n-2), with initial conditions F(1) = F(2) = 1.
Input:
...read more
Ans. 
Calculate the Nth Fibonacci number efficiently using dynamic programming.
• Use dynamic programming to store and reuse previously calculated Fibonacci numbers.

• Start with base cases F(1) and F(2) as 1, then calculate subsequent Fibonacci numbers.

• Optimize the solution to avoid redundant calculations by storing intermediate results.

• Time complexity can be reduced to O(N) using dynamic programming.
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Round duration - 60 minutes
Round difficulty - Easy

DSA questions based on trees were asked to implement.

Q1. 
Determine the Left View of a Binary Tree
You are given a binary tree of integers. Your task is to determine the left view of the binary tree. The left view consists of nodes that are visible when the tree...read more
Ans. 
The task is to determine the left view of a binary tree, which consists of nodes visible when viewed from the left side.
• Traverse the binary tree level by level from left to right, keeping track of the first node encountered at each level.

• Use a queue to perform level order traversal of the binary tree.

• Store the leftmost node at each level in the result array.

• Return the result array containing the left view of the binary
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Q2. 
Right View of Binary Tree
Given a binary tree of integers, your task is to output the right view of the tree.
The right view of a binary tree includes the nodes that are visible when the tree is observed...read more
Ans. 
The task is to output the right view of a binary tree, which includes the nodes visible when observed from the right.
• Perform level order traversal of the binary tree.

• For each level, add the rightmost node to the result.

• Print the result as the right view of the binary tree.

• Handle null nodes represented by -1 in the input.
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Q3. 
Height of Binary Tree
You are provided with the Inorder and Level Order traversals of a Binary Tree composed of integers. Your goal is to determine the height of this Binary Tree without actually construc...read more
Ans. 
Find the height of a Binary Tree given its Inorder and Level Order traversals without constructing it.
• Use the properties of Inorder and Level Order traversals to determine the height of the Binary Tree.

• The height of a Binary Tree is the number of edges on the longest path from the root to a leaf node.

• Consider edge cases like a single node tree or empty tree while calculating the height.
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Round duration - 30 minutes
Round difficulty - Easy

Typical HR round where the interviewer asked questions to know more about me.