98thPercentile Senior Software Developer Interview Questions and Answers

It was on hacker rank

It was a aptitude test taken by me of the new and all the response and the of new

2 coding questions with aptitude question(logical aptitude and quantitative aptitude)

This was a Machine Coding. We need to design a system and then they will check our design by running test cases. It was 2.5 hrs long.

Q1. Basic questions on computer core subjects(Deadlock, Networking, Tcp connection, process scheduling etc, DNS Lookup etc)
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Q2. Questions on React, Node and the libraries which I used in my project(My project was a full stack project)
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Implement login with Google SSO, show emails in a single place

Q1. How to implement JWT
Ans. 
JWT can be implemented by generating a token with user information and a secret key, then verifying the token using the same secret key.
• Generate a JWT token with user information and a secret key

• Include necessary claims like expiration time, issuer, etc.

• Verify the JWT token using the same secret key

• Handle token expiration and refresh if needed
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Q2. Please read about it on the internet, do take care of public and private key use
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Q3. Middleware in express, how to create one?
Ans. 
Middleware in Express is a function that has access to the request and response objects.
• Create a middleware function using app.use() method in Express.

• Middleware functions have access to the request object (req), the response object (res), and the next middleware function in the application's request-response cycle.

• Example: app.use((req, res, next) => { console.log('This is a middleware function'); next(); });
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Q4. Read about it on the internet
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Q1. Discussed about guards in Angular
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Q2. Read about it on the internet
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Q3. How does lazy loading work in Angular
Ans. 
Lazy loading in Angular delays loading of modules until they are needed
• Lazy loading helps improve performance by only loading modules when they are required

• It is achieved by using the loadChildren property in the route configuration

• Lazy loaded modules are loaded asynchronously when the user navigates to the corresponding route
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Q4. Read about lazy loading in Angular
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Q5. How to enable SSR in Angular
Ans. 
Server-side rendering (SSR) in Angular can be enabled by using Angular Universal.
• Install Angular Universal using Angular CLI

• Create a new Angular Universal project

• Update app.module.ts to include server-side rendering

• Build and run the Angular Universal project
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Q6. Read about Angular Universal for this
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Q1. Find duplicates in an array
Ans. 
Use a hash set to find duplicates in an array of strings.
• Create a hash set to store unique elements.

• Iterate through the array and check if the element is already in the hash set.

• If it is, then it is a duplicate. If not, add it to the hash set.
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Q2. Find single duplicate element in an array where contents of the array are length of array - 1
Ans. 
Find the single duplicate element in an array of strings with length n-1.
• Iterate through the array and use a HashSet to keep track of elements seen so far.

• If an element is already in the HashSet, that is the duplicate element.

• Return the duplicate element once found.
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Create a student support system

Q1. Design an order and payments system for an EdTech company
Ans. 
Design an order and payments system for an EdTech company
• Allow users to browse and select courses

• Implement a shopping cart for users to add courses

• Integrate payment gateways for secure transactions

• Provide order confirmation and receipt to users

• Allow users to track their order status
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Explain about DSA and its example in realtime.

Basic aptitude questions

Linked list, array, tree and graph questions

Basic coding and MySQL queries. Like Types of join, having and where difference etc.

Q1. Salary Discussion.
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Round duration - 60 minutes
Round difficulty - Easy

Q1. 
Path Queries Problem Statement
Consider a weighted, undirected graph with 'V' vertices numbered from 1 to 'V' and 'E' bidirectional edges. You are tasked with handling 'Q' queries. For each query, you are...read more
Ans. 
Implement a function to find the shortest distance between two vertices in a weighted, undirected graph.
• Use Dijkstra's algorithm to find the shortest path between the given vertices.

• Create a graph data structure to represent the weighted, undirected graph.

• Handle cases where no path exists between the given vertices by returning -1.

• Optimize the algorithm to handle multiple queries efficiently.

• Consider edge cases such as...read more
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Q2. 
Merge Sort Algorithm Problem Statement
Your task is to sort a sequence of numbers stored in the array ‘ARR’ in non-descending order using the Merge Sort algorithm.
Explanation:
Merge Sort is a divide-an...read more
Ans. 
Implement Merge Sort algorithm to sort a sequence of numbers in non-descending order.
• Divide the input array into two halves recursively

• Sort the two halves separately

• Merge the sorted halves to produce a fully sorted array

• Time complexity of Merge Sort is O(n log n)

• Example: Input - [5, 2, 9, 1, 5], Output - [1, 2, 5, 5, 9]
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Q3. 
Rat in a Maze: All Paths Problem
You are provided with an N * N maze where a rat is positioned at starting cell MAZE[0][0]. The goal is to determine and print all possible paths that the rat can take to r...read more
Ans. 
Given an N * N maze with binary values, find and print all possible paths for a rat to reach the destination cell.
• Use backtracking to explore all possible paths from the starting cell to the destination cell.

• At each cell, check if it is a valid move (within bounds and not blocked), then recursively explore all four directions.

• Keep track of the path taken so far and mark the cells accordingly.

• Once the destination cell i...read more
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