70+ Sdet Lead Interview Questions and Answers

The candidate was asked various questions related to software development and testing.

• To write a palindrome program without using any in-built method, the candidate can use a loop to compare characters from both ends of the string.

• To approach and run only 50 out of 500 test cases, the candidate can prioritize the test cases based on criticality and execute the most important ones first.

• The framework used in the candidate's project was not mentioned.

• To handle a team member's a...read more

Answers to interview questions for Sdet Lead position

• 1. FluentWait syntax: FluentWait wait = new FluentWait<>(driver)

• 2. To scroll to the bottom of the page in Selenium, you can use JavaScriptExecutor or Actions class

• 3. Syntax for Implicit Wait: driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS)

• Implicit Wait is not part of Overloading or Overriding

• 4. JavaScriptExecutor is an interface in Selenium that allows executing JavaScript code in the context of the current...read more

Reverse the whole string with spaces remaining in the same place

• Iterate through the string and reverse each word individually

• Keep track of spaces and add them back in the reversed string

• Join the reversed words together to form the final reversed string

OOPs is Object-Oriented Programming, CSS is Cascading Style Sheets, HTML is Hypertext Markup Language. Batch processing is a method of processing data in groups.

• OOPs is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• CSS is used for styling web pages and controlling their layout. It stands for Cascading Style Sheets.

• HTML is the standard markup language for creating web pages. It stands for...read more

The median of two sorted arrays can be found in O(log n) time using binary search.

• Divide the arrays into two parts at a certain index and compare the medians of both parts.

• Adjust the dividing index based on the comparison until the medians are equal or adjacent.

• Handle edge cases like uneven array lengths and one array being entirely smaller than the other.

Python program to hit get call and fetch required details.

• Use the requests library to make a GET request to the desired URL

• Extract the required details from the response using JSON parsing or other methods

• Handle any errors or exceptions that may occur during the process

Event loop is a mechanism that allows for asynchronous programming by handling and executing events in a loop.

• Event loop is a part of the runtime environment that continuously checks the event queue and executes the callback functions associated with the events.

• It helps in managing non-blocking I/O operations efficiently by allowing the program to continue running while waiting for I/O operations to complete.

• Event loop is commonly used in JavaScript for handling asynchronous ...read more

Database warehousing is the process of collecting, storing, and managing data from various sources for analysis and reporting.

• Database warehousing involves extracting data from different sources

• Data is transformed and loaded into a central repository for analysis

• It allows for complex queries and reporting on large datasets

• Examples include data warehouses like Amazon Redshift, Google BigQuery

Disjoint set union method is a data structure used to efficiently merge two sets and find the parent set of an element in a graph.

• Disjoint set union method is also known as Union-Find data structure.

• It consists of two main operations: union (merge two sets) and find (determine the parent set of an element).

• Path compression and union by rank are common optimizations used in disjoint set union method.

• Example: In a graph with nodes representing cities, disjoint set union can be ...read more

React is a JavaScript library for building user interfaces, while Vue.js is a progressive JavaScript framework for building web interfaces.

• React is a library, while Vue.js is a framework

• React uses a virtual DOM for better performance, while Vue.js uses a virtual DOM as well but with a different approach

• React has a larger community and ecosystem compared to Vue.js

• React is more flexible and allows for more customization, while Vue.js is easier to learn and use for beginners

Trees are data structures that consist of nodes connected by edges, with a root node at the top. Balanced trees are trees where the heights of subtrees differ by at most one.

• Trees are hierarchical data structures with a root node and child nodes.

• Balanced trees are trees where the heights of subtrees differ by at most one, ensuring efficient search and insertion operations.

• Examples of balanced trees include AVL trees, red-black trees, and B-trees.

Debugging an application involves identifying and fixing issues in the code, while writing test cases ensures the application functions correctly.

• Understand the functionality of the application and identify the root cause of the issue

• Use debugging tools like breakpoints, logging, and stack traces to pinpoint the problem

• Write test cases to cover different scenarios and ensure the issue is resolved

• Reproduce the issue to validate the fix and prevent regression

• Document the debugg...read more

Visible nodes in a binary tree are the nodes that are not blocked by any other nodes when viewed from below.

• Traverse the binary tree level by level and keep track of the maximum value seen at each level. Any node with a value greater than the maximum value seen so far is considered a visible node.

• Example: For a binary tree with values [5, 3, 8, 1, 4, 7, 9], the visible nodes from below would be [5, 8, 9].

Design a central logging system for efficient monitoring and troubleshooting.

• Use a centralized server to collect logs from all systems

• Implement log aggregation tools like ELK stack or Splunk

• Set up alerts for critical errors or anomalies

• Ensure secure access controls for log data

• Consider scalability and storage requirements

Architectural design patterns are reusable solutions to common problems encountered in software design.

• Architectural design patterns provide guidelines on how to structure and organize software systems.

• Examples include MVC (Model-View-Controller), MVVM (Model-View-ViewModel), and Layered Architecture.

• They help improve the scalability, maintainability, and flexibility of software applications.

QuickSort is one of the best sorting algorithms with an average time complexity of O(n log n).

• QuickSort is a divide and conquer algorithm that works by selecting a 'pivot' element and partitioning the array around the pivot.

• It has an average time complexity of O(n log n) and a worst-case time complexity of O(n^2).

• Example: ['apple', 'banana', 'cherry', 'date', 'fig'] can be sorted using QuickSort.

• Example: ['3', '1', '4', '1', '5', '9', '2', '6', '5'] can be sorted using QuickS...read more

An abstract class is a class that cannot be instantiated and may contain abstract methods that must be implemented by its subclasses.

• Cannot be instantiated directly

• May contain abstract methods

• Used as a blueprint for other classes

To find the shortest distance between two nodes, we can use algorithms like Dijkstra's or A*.

• Use Dijkstra's algorithm to find the shortest path between two nodes in a graph

• Implement A* algorithm for finding the shortest path in a grid-based environment

• Consider using Floyd-Warshall algorithm for finding all pairs shortest paths in a graph

Testing a lift system involves multiple steps to ensure its functionality and safety.

• 1. Verify the lift system's basic functionality such as going up and down smoothly.

• 2. Test emergency stop functionality to ensure safety measures are in place.

• 3. Check for proper alignment of doors and sensors to prevent accidents.

• 4. Conduct load testing to ensure the lift can handle its maximum capacity.

• 5. Test communication systems between the lift and control panel for seamless operation.

Reverse the kth node in a linked list

• Traverse the linked list to find the kth node

• Reverse the kth node by changing its next pointer to point to the previous node

• Update the pointers of the previous and next nodes accordingly

• Handle edge cases such as k being out of bounds or kth node being the head of the list

BTEE stands for Breadth-First Tree Enumeration and it is a method used to traverse a tree data structure.

• BTEE is a technique used to visit all the nodes of a tree level by level, starting from the root node.

• It uses a queue data structure to keep track of the nodes to be visited next.

• BTEE ensures that all nodes at the same level are visited before moving on to the next level.

Method overriding is a feature in object-oriented programming where a subclass provides a specific implementation of a method that is already provided by its superclass.

• In method overriding, the method in the subclass has the same name, return type, and parameters as the method in the superclass.

• The method in the subclass must have the same or wider access modifier than the method in the superclass.

• Method overriding allows for polymorphism, where a subclass object can be trea...read more

Hashing in DSA is a technique used to map data to a fixed-size array, allowing for efficient data retrieval.

• Hashing involves using a hash function to generate a unique value for each input data.

• The hash value is used as an index to store or retrieve data in a data structure like a hash table.

• Common hash functions include MD5, SHA-1, and SHA-256.

• Hashing is used in various applications like password storage, data retrieval, and cryptography.

Python is a versatile and powerful programming language known for its simplicity and readability.

• Python is easy to learn and has a clear and concise syntax.

• It has a large standard library with built-in modules for various tasks.

• Python supports multiple programming paradigms, including procedural, object-oriented, and functional programming.

• It is widely used in web development, data analysis, artificial intelligence, and automation.

• Python has a strong and active community, pro...read more

Breadth First Search is a graph traversal algorithm that explores all the neighbor nodes at the present depth prior to moving on to the nodes at the next depth level.

• BFS starts at the root node and explores all of the neighbor nodes at the present depth before moving on to the nodes at the next depth level.

• It uses a queue data structure to keep track of the nodes to be visited.

• BFS is often used in shortest path and minimum spanning tree algorithms.

• Example: Finding the shortes...read more

Dynamic programming is a method for solving complex problems by breaking them down into simpler subproblems and storing the solutions to avoid redundant calculations.

• Dynamic programming involves breaking down a problem into smaller subproblems and solving each subproblem only once.

• It is used to optimize solutions by storing the results of subproblems to avoid redundant calculations.

• Examples include Fibonacci sequence calculation, shortest path algorithms, and knapsack problem...read more

Reverse a string using array of characters

• Convert the string to an array of characters

• Use a loop to iterate through the array in reverse order

• Append each character to a new string to form the reversed string

Strings are immutable in order to ensure data integrity and security.

• Immutable strings prevent accidental changes to data.

• Immutable strings allow for safe sharing of data between different parts of a program.

• Immutable strings help in multithreading environments by avoiding race conditions.

• Example: String str = "hello"; str.concat(" world"); // This will create a new string instead of modifying the original one.

OOPs concepts refer to Object-Oriented Programming principles that focus on objects, classes, inheritance, encapsulation, and polymorphism.

• Objects: Instances of classes that encapsulate data and behavior

• Classes: Blueprint for creating objects with attributes and methods

• Inheritance: Ability for a class to inherit properties and behavior from another class

• Encapsulation: Binding data and methods that operate on the data into a single unit

• Polymorphism: Ability for objects of diff...read more

LFU cache design in a distributed manner

• Use a distributed key-value store like Redis to store the cache data

• Implement a distributed algorithm to track the frequency of cache access across nodes

• Use a consensus algorithm like Raft or Paxos to ensure consistency in cache eviction policies

Design a distributed LRU cache system for efficient data storage and retrieval.

• Implement a distributed cache system using a combination of local caches on each node and a centralized cache for coordination.

• Use a consistent hashing algorithm to determine which node should store each key-value pair.

• Implement a cache eviction policy based on LRU (Least Recently Used) to remove the least recently accessed items when the cache is full.

• Use a distributed messaging system for cache i...read more

Java design patterns are reusable solutions to common problems encountered in software design.

• Java design patterns help in creating flexible, reusable, and maintainable code.

• Examples of Java design patterns include Singleton, Factory, Observer, and Strategy.

• Design patterns can be categorized into three groups: creational, structural, and behavioral.

SDLC stands for Software Development Life Cycle, which is a process used by software development teams to design, develop, and test high-quality software.

• SDLC is a structured process that consists of several phases such as planning, analysis, design, implementation, testing, and maintenance.

• Each phase of SDLC has specific goals and deliverables that must be completed before moving on to the next phase.

• Examples of SDLC models include Waterfall, Agile, and DevOps, each with its...read more

Iterate through the array and return the last element

• Iterate through the array using a loop

• Keep track of the last element as you iterate

• Return the last element once the loop is finished

Abstraction is the process of hiding complex details and showing only the essential features of an object or system.

• Abstraction allows us to focus on what an object does, rather than how it does it

• It helps in simplifying complex systems by breaking them down into smaller, more manageable parts

• Examples of abstraction include using a car without needing to understand its internal combustion engine, or using a smartphone without knowing its hardware components

Use StringBuilder class to reverse a string in Java.

• Create a StringBuilder object with the input string.

• Use the reverse() method of StringBuilder to reverse the string.

• Convert the reversed StringBuilder object back to a string using toString() method.

DBMS schooling typically includes courses in database design, implementation, management, and querying.

• Courses in database design cover topics such as normalization, ER modeling, and schema design.

• Implementation courses focus on creating and maintaining databases using tools like SQL Server or Oracle.

• Management courses teach skills related to backup, recovery, security, and performance tuning.

• Querying courses cover SQL syntax, joins, subqueries, and optimization techniques.

Check if a given string is a palindrome

• Iterate through the string from both ends and compare characters

• Ignore spaces and punctuation marks while checking for palindrome

• Convert the string to lowercase for case-insensitive comparison

Designing a system for a Netflix-like app involves considerations for scalability, high availability, and personalized recommendations.

• Use microservices architecture for scalability and flexibility.

• Implement a content delivery network (CDN) for fast and reliable streaming.

• Utilize machine learning algorithms for personalized recommendations.

• Include a robust user authentication and authorization system.

• Implement caching mechanisms to reduce latency and improve performance.

Ratelimiting APIs is a crucial aspect of ensuring system stability and preventing abuse.

• Implement rate limiting to restrict the number of API calls a user can make within a specific time frame.

• Use tokens or counters to track and enforce rate limits.

• Consider using a distributed cache or database to store rate limit data for scalability.

• Monitor and adjust rate limits based on usage patterns and system performance.

• Provide informative error messages when rate limits are exceeded ...read more

Process life cycle refers to the stages a process goes through from creation to completion.

• Includes stages like initiation, planning, execution, monitoring, and closure

• Each stage has specific tasks and objectives to be completed

• Example: Software development process life cycle includes requirements gathering, design, coding, testing, and deployment

Object-oriented programming features include encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (class).

• Inheritance: Ability for a class to inherit properties and behavior from another class.

• Polymorphism: Ability for objects of different classes to respond to the same message in different ways.

• Abstraction: Hiding the complex implementation details and showing only the necessary feature...read more

Designing a Content Delivery Network (CDN) for efficient content distribution.

• Identify target audience and content types

• Select appropriate CDN providers based on needs (e.g. Akamai, Cloudflare)

• Implement caching strategies for static and dynamic content

• Optimize network routing for faster delivery

• Monitor performance and adjust as needed

Object-oriented programming concepts that focus on classes, objects, inheritance, encapsulation, and polymorphism.

• Classes: Blueprint for creating objects with attributes and methods.

• Objects: Instances of classes that contain data and behavior.

• Inheritance: Ability for a class to inherit attributes and methods from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability for objects of different classes to respond ...read more

Recursion is a programming concept where a function calls itself in order to solve a problem.

• Recursion involves breaking down a problem into smaller subproblems and solving them recursively.

• A base case is needed to stop the recursion and prevent infinite loops.

• Examples include factorial calculation, Fibonacci sequence, and tree traversal.

OS in CSE stands for Operating System in Computer Science Engineering.

• OS is a software that manages computer hardware and provides services for computer programs.

• It acts as an intermediary between computer hardware and software applications.

• Examples of OS include Windows, macOS, Linux, and Unix.

I have led multiple projects in test automation, performance testing, and CI/CD implementation.

• Led a team in developing automated test scripts using Selenium for web applications

• Implemented performance testing using JMeter to identify bottlenecks in the system

• Set up CI/CD pipelines using Jenkins for continuous integration and deployment

• Worked on integrating test automation with Docker containers for efficient testing

• Collaborated with development teams to ensure test coverage ...read more