Licious Software Engineer Interview Questions and Answers

Basics of Frontend development and project discussion

Round duration - 60 Minutes
Round difficulty - Medium

This round was purely based on Data Structures and Algorithms . One has to be fairly comfortable in solving Algorithmic problems to pass this round . Both the questions asked were quite common and luckily I had already prepared them from CodeStudio and LeetCode.

Q1. 
Binary Tree Traversals Problem Statement
Given a Binary Tree with 'N' nodes, where each node holds an integer value, your task is to compute the In-Order, Pre-Order, and Post-Order traversals of the binar...read more
Ans. 
Compute the In-Order, Pre-Order, and Post-Order traversals of a Binary Tree given in level-order format.
• Implement functions to perform In-Order, Pre-Order, and Post-Order traversals of a Binary Tree.

• Use level-order input to construct the Binary Tree.

• Traverse the Binary Tree recursively to generate the required traversals.

• Ensure proper handling of null nodes represented by -1 in the input.

• Return the three traversals as
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Q2. 
Reverse Linked List Problem Statement
Given a Singly Linked List of integers, your task is to reverse the Linked List by altering the links between the nodes.
Input:
The first line of input is an intege...read more
Ans. 
Reverse a singly linked list by altering the links between nodes.
• Iterate through the linked list and reverse the links between nodes

• Use three pointers to keep track of the current, previous, and next nodes

• Update the links between nodes to reverse the list

• Return the head of the reversed linked list
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Round duration - 45 Minutes
Round difficulty - Medium

This round basically tested some concepts from Data Structures and File Manipulation .

Q1. 
Intersection of Two Arrays Problem Statement
Given two arrays A and B with sizes N and M respectively, both sorted in non-decreasing order, determine their intersection.
The intersection of two arrays in...read more
Ans. 
The problem involves finding the intersection of two sorted arrays efficiently.
• Use two pointers to iterate through both arrays simultaneously.

• Compare elements at the pointers and move the pointers accordingly.

• Handle cases where elements are equal and update the intersection array.

• Return the intersection array as the result.
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Q1. Code postorder traversal without using recursion.
Ans. 
Iterative solution using a stack to perform postorder traversal.
• Use a stack to simulate the recursive call stack.

• Push nodes in the order of right, left, root.

• Pop nodes from stack and add to result array.

• Repeat until stack is empty.
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Q2. Leetcode Problem 1626 - Best team with no conflicts.
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Q1. Design whatsapp with one to one, group messaging and read receipts functionalities. Design the database.
Ans. 
Design a messaging app like WhatsApp with one-to-one, group messaging, and read receipts functionalities.
• Use a relational database to store user information, messages, and group memberships.

• Create tables for users, messages, groups, and group memberships.

• Include columns for message content, sender, receiver, timestamp, and read status.

• Implement a feature to mark messages as read with read receipts.

• Use indexes for effic
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Q2. Questions on dbms, cn and os.
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Round duration - 120 minutes
Round difficulty - Medium

Round duration - 120 minutes
Round difficulty - Medium

- Discussion on the first round's assignment
- Was asked about adding unit tests in the assignment
- Fundamental questions on the approach used for the assignment.

Q1. What are some things that could have been done better in the system design problem given in the first round?
Ans. 
Some improvements in the system design problem could include better scalability planning, more efficient data storage solutions, and improved error handling.
• Implementing a more robust caching mechanism to improve performance under heavy load.

• Optimizing the database schema for better query performance and scalability.

• Introducing load balancing and horizontal scaling to handle increased traffic.

• Enhancing error handling t...read more
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Round duration - 90 minutes
Round difficulty - Medium

Round was with tech lead. Was briefly asked about the problem I solved in the first round. Then I was asked to solve 1 medium level DSA based question. Some discussion on culture fit was also done.

Q1. Given the frequency of traffic lights' states, can you determine if there will ever be an invalid state for the traffic signal, and what are the conditions that lead to an invalid state?
Ans. 
Yes, an invalid state can occur if the traffic lights are in conflicting states simultaneously.
• An invalid state occurs when multiple traffic lights are showing conflicting signals, such as both red and green at the same time.

• This can happen due to a malfunction in the traffic light system or human error in programming the lights.

• For example, if a traffic light is stuck showing both red and green signals, it would be co
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3D DP, DP ON BST, Focus on highlevel dp and system design

Round duration - 120 Minutes
Round difficulty - Medium

Machine Coding Round
2 Hours in Total
15 Mins for Question Explaination and Doubts
1.5 Hours for coding
15 mins to discuss the approach 

Timing - 3 to 5 pm (They are flexible)
Interviewer was very patient and helped me understand the question

Round duration - 60 Minutes
Round difficulty - Medium

2 Data Strucutre Questions
Timing 5-6 pm (They are flexible)
Google Meet
Online IDE

Q1. 
Unique Binary Search Trees Problem Statement
Given an integer 'N', your task is to compute the number of structurally unique BSTs (binary search trees) that can be formed using an exact number of 'N' uniq...read more
Ans. 
The task is to compute the number of structurally unique BSTs that can be formed using an exact number of unique values.
• Use dynamic programming to solve the problem efficiently.

• The number of structurally unique BSTs can be calculated using Catalan numbers.

• For N nodes, the number of structurally unique BSTs is given by the Nth Catalan number.

• Example: For N=3, the number of structurally unique BSTs is 5.
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Q2. 
Subsequences of String Problem Statement
You are provided with a string 'STR' that consists of lowercase English letters ranging from 'a' to 'z'. Your task is to determine all non-empty possible subsequen...read more
Ans. 
Generate all possible subsequences of a given string.
• Use recursion to generate all possible subsequences by including or excluding each character in the string.

• Maintain a current index to keep track of the characters being considered.

• Append the current character to each subsequence generated so far.

• Recursively call the function with the next index to include or exclude the next character.

• Base case: When the current ind...read more
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Round duration - 60 Minutes
Round difficulty - Easy

HIRING MANAGER ROUND

Discussion about the organisation now questions

HAckerrank based test