Gap Senior Software Engineer Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Medium

Round duration - 60 minutes
Round difficulty - Medium

This was the technical round, held around at 10 AM IST on Google Meet.
Firstly she greeted me and asked me to tell something about myself, to which I introduced myself, explaining my academic and some projects also.
After that we moved on to the Hackathon project, which was smart cart self-checkout system. I explained the project along with the code, wherever necessary.
Every word you say while explaining should be clear to you.I used Firebase and SQL while explaining my project, to which she asked some questions related to it, 
Then she moved to the DBMS part, types of joins,what is indexing, how to approach if you were to design a payment system.
At last she asked me some Data Structure questions, which were of medium complexity

Q1. 
Remove the Kth Node from the End of a Linked List
You are given a singly Linked List with 'N' nodes containing integer data and an integer 'K'. Your task is to delete the Kth node from the end of this Lin...read more
Ans. 
Remove the Kth node from the end of a singly linked list given the position 'K'.
• Traverse the list to find the length 'N' of the linked list.

• Calculate the position of the node to be removed from the beginning as 'N - K + 1'.

• Traverse the list again and remove the node at the calculated position.
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Q2. 
House Robber Problem Statement
Consider Mr. X, a professional robber who is planning to rob houses along a street. These houses are arranged in a circle, which means the first house is a neighbor to the l...read more
Ans. 
House Robber problem where adjacent houses have connected security system, find maximum money Mr. X can rob without triggering security.
• Use dynamic programming to keep track of maximum money robbed at each house.

• At each house, decide whether to rob the current house or skip it based on maximum money robbed so far.

• Handle the circular nature of houses by considering two cases: robbing the first house and not robbing the ...read more
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Round duration - 30 minutes
Round difficulty - Easy

The interviewer was very frank and cheerful. This was held at 2:30 PM IST on Google Meet.
He firstly greeted me and asked me how I was doing.
How was my previous round, any technical difficulties?
Then he asked me to introduce myself.
He started telling about his journey to Lowe's and his technical background.
Then he asked some HR related questions

Round duration - 60 Minutes
Round difficulty - Medium

There were 2 coding questions given in this round. One was related to Dynamic Programming and the second one was related to Recursion and Number Theory.

Q1. 
House Robber Problem Statement
Mr. X is a professional robber with a plan to rob houses arranged in a circular street. Each house has a certain amount of money hidden, separated by a security system that ...read more
Ans. 
House Robber problem where a robber wants to maximize stolen money without robbing adjacent houses in a circular street.
• Use dynamic programming to keep track of maximum stolen money at each house.

• Consider two cases: either rob the current house and skip the next, or skip the current house.

• Handle circular arrangement by considering the first and last houses separately.

• Example: For arr[] = {2, 3, 2}, the output is 3. Rob...read more
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Q2. 
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.

• Example: For N = 5, the 5th F
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Round duration - 50 Minutes
Round difficulty - Medium

Standard Data Structures and Algorithms round where I was given 2 questions to solve , one was from Linked List and the other was related to Priority Queue / Quick Sort .

Q1. 
Intersection of Linked Lists Problem Statement
You are provided with two linked lists, L1 and L2, both sorted in ascending order. Generate a new linked list containing elements that exist in both linked l...read more
Ans. 
Given two sorted linked lists, find the intersection of elements in both lists and return a new sorted linked list.
• Traverse both linked lists simultaneously to find common elements

• Create a new linked list to store the intersecting elements

• Ensure the final linked list is sorted in ascending order

• Handle cases where there are no common elements between the lists
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Q2. 
Kth Largest Element Problem Statement
Ninja enjoys working with numbers, and Alice challenges him to find the Kth largest value from a given list of numbers.
Input:
The first line contains an integer 'T...read more
Ans. 
Find the Kth largest element in a given list of numbers.
• Sort the array in descending order.

• Return the Kth element from the sorted array.

• Handle multiple test cases efficiently.
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Round duration - 50 Minutes
Round difficulty - Easy

This round majorly focused on Real life appications of Data Structures and also revolved around Object Oriented Programming Style of writing code .

Q1. 
Data Structure with Insert, Delete, and GetRandom Operations
Design a data structure that supports four operations: insert an element, remove an element, search for an element, and get a random element. E...read more
Ans. 
Design a data structure with insert, delete, search, and getRandom operations, all in constant time.
• Use a combination of HashMap and ArrayList to achieve constant time operations.

• For insert operation, add the element to the ArrayList and store its index in the HashMap.

• For delete operation, swap the element to be deleted with the last element in the ArrayList, update the index in the HashMap, and then remove the last el...read more
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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 constraint.
• Implement a doubly linked list to maintain the order of keys based on their recent usage.

• Use a hashmap to store key-value pairs for quick access.

• When capacity is reached, evict the least recently used item before inserting a new item.

• Update the position of a key in the linked list whenever it is accesse
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Round duration - 45 Minutes
Round difficulty - Medium

This round was inclined towards some Low Level Design Principles and some concepts from Java .

Q1. Design a Railway Reservation System.
Ans. 
Design a Railway Reservation System
• Create a database to store train schedules, seat availability, and passenger information

• Implement a user interface for users to search for trains, book tickets, and view their reservations

• Include features like seat selection, payment processing, and ticket confirmation

• Handle scenarios like waitlisting, cancellations, and refunds

• Ensure data security and privacy of passenger information
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Q2. Why is Java considered platform-independent while the Java Virtual Machine (JVM) is platform-dependent?
Ans. 
Java is platform-independent because the code is compiled into bytecode that can run on any platform with a JVM, which is platform-dependent due to its reliance on the underlying hardware and operating system.
• Java code is compiled into bytecode, which can run on any platform with a JVM.

• JVM acts as an interpreter that translates bytecode into machine code specific to the underlying hardware and operating system.

• The JVM ...read more
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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. 
Minimum Cost to Buy Oranges Problem Statement
You are given a bag of capacity 'W' kg and a list 'cost' of costs for packets of oranges with different weights. Each element at the i-th position in the list...read more
Ans. 
Find the minimum cost to buy a specific weight of oranges using given cost list.
• Iterate through the cost list and find the minimum cost to achieve the desired weight

• Keep track of the minimum cost while considering available packet weights

• Return -1 if it is not possible to buy exactly W kg of oranges
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Q2. 
K - Sum Path In A Binary Tree
Given a binary tree where each node contains an integer value, and a value 'K', your task is to find all the paths in the binary tree such that the sum of the node values in ...read more
Ans. 
Find all paths in a binary tree where the sum of node values equals a given value 'K'.
• Traverse the binary tree using DFS and keep track of the current path and its sum.

• At each node, check if the current sum equals 'K' and add the path to the result if true.

• Continue traversal to the left and right child nodes recursively.

• Return the list of paths that sum up to 'K'.
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Round duration - 40 Minutes
Round difficulty - Medium

This round majorly focused on puzzles and some questions revolving around Computer Networks and the projects in my resume .

Q1. You have two wires of different lengths that take different times to burn. How can you measure a specific amount of time using these two wires?
Ans. 
Use two wires of different lengths to measure a specific amount of time by burning them simultaneously.
• Burn both wires at the same time, one wire will burn faster than the other.

• Measure the time it takes for the faster burning wire to completely burn.

• Calculate the specific amount of time by using the ratio of the lengths of the two wires.
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Q2. You have 3 ants located at the corners of a triangle. The challenge is to determine the movement pattern of the ants if they all start moving towards each other. What will be the outcome?
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my role.

Q1. What do you know about the company?
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Q2. Why should we hire you?
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