60+ Software Development Engineer 1 Interview Questions and Answers

Design a system for making table reservations at a restaurant.

• Create a user-friendly interface for customers to make reservations

• Allow customers to select date, time, and party size

• Provide real-time updates on table availability

• Integrate with the restaurant's seating chart and reservation system

• Send confirmation emails or texts to customers

• Allow customers to modify or cancel reservations

• Provide analytics for the restaurant to track reservations and customer behavior

To find binary tree from preorder and postorder, use recursion and divide the arrays into left and right subtrees.

• Create a binary tree node using the first element of preorder array

• Find the root node's index in postorder array

• Divide the arrays into left and right subtrees recursively

To create a Spring Boot application, you can use Spring Initializr to generate a project with necessary dependencies and configurations.

• Go to https://start.spring.io/

• Select the project metadata like group, artifact, dependencies, etc.

• Click on 'Generate' to download the project zip file.

• Extract the zip file and import the project into your IDE.

• Start coding your Spring Boot application.

Spring Boot dependency management is a feature that simplifies managing dependencies in a Spring Boot project.

• Spring Boot uses Maven or Gradle for dependency management

• Dependencies are declared in the pom.xml file for Maven or build.gradle file for Gradle

• Spring Boot provides a 'starter' dependencies that include commonly used libraries and frameworks

• Version conflicts are resolved automatically by Spring Boot

Default method in Java 8 allows interfaces to have method implementations.

• Introduced in Java 8 to provide backward compatibility for interfaces

• Default methods can be overridden by implementing classes

• Used to add new methods to interfaces without breaking existing implementations

To find a bug in a React problem

• Check the console for any error messages

• Use React Developer Tools to inspect the component tree and state

• Check if the props and state are being updated correctly

• Check if the lifecycle methods are being called in the correct order

• Check if the event handlers are bound correctly

• Check if the JSX syntax is correct

Polymorphism is the ability of a function or method to behave differently based on the object it is called with.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: Inheritance allows a child class to override a method from its parent class, providing different functionality.

Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope during compilation.

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted, including their definitions.

• Hoisting can lead to unexpected behavior if not understood properly.

Indexing in NoSQL is a technique used to optimize query performance by creating data structures that allow for faster data retrieval.

• Indexes in NoSQL databases are similar to indexes in relational databases, but they are typically more flexible and can be created on any field in a document.

• By creating indexes on specific fields, queries can quickly locate the desired data without having to scan through the entire database.

• Indexes can be created as single-field indexes or comp...read more

Closure is a function that has access to its parent scope even after the parent function has returned.

• Closure is used for data privacy and encapsulation.

• It allows functions to have private variables that cannot be accessed from outside the function.

• It can be used to create factory functions that generate new functions with specific behavior.

• It is also used in event handling and callbacks.

• Example: function outer() { let x = 10; function inner() { console.log(x); } return inner...read more

Annotation used in Spring framework to indicate that a class is a RESTful controller

• Used in Spring framework to define RESTful web services

• Eliminates the need for annotating every method with @ResponseBody

• Combines @Controller and @ResponseBody annotations

Calculate the area under a graph using numerical integration.

• Use numerical integration methods like trapezoidal rule or Simpson's rule to approximate the area under the curve.

• Divide the graph into small segments and calculate the area of each segment, then sum them up to get the total area.

• Make sure to handle cases where the graph is below the x-axis by taking the absolute value of the function before calculating the area.

Remove duplicates from a list

• Create a new empty list

• Loop through the original list

• If an element is not in the new list, add it

• Return the new list

Moodle database is a database system used by the Moodle learning management system to store and manage user data, course information, and other related data.

• Moodle database stores user profiles, course content, grades, and other information related to online learning.

• It uses a relational database management system like MySQL or PostgreSQL to store data.

• The database schema is designed to support the various features and functionalities of the Moodle platform.

• Queries can be run...read more

Callback hell is a situation where multiple nested callbacks make the code difficult to read and maintain.

• Use named functions instead of anonymous functions to make the code more readable.

• Use promises or async/await to handle asynchronous operations in a more organized way.

• Break down complex functions into smaller, reusable functions to avoid deep nesting.

• Use libraries like async.js or lodash to handle asynchronous operations more efficiently.

Lambda expression is a concise way to represent an anonymous function in programming languages.

• Lambda expressions are used to create functions without a name.

• They are often used in functional programming languages like Python and Java.

• Lambda expressions can be passed as arguments to higher-order functions.

• They are commonly used for short, one-off functions.

• Example: (x) => x * x is a lambda expression that squares a number.

Optimise solution for scheduling doctors appointments

• Use a priority queue to keep track of available time slots

• Implement a system to handle overlapping appointments

• Consider implementing a waitlist for patients if all slots are full

Use depth-first search or breadth-first search to find a path in a maze graph.

• Implement a graph representation of the maze using an adjacency list or matrix.

• Use depth-first search (DFS) or breadth-first search (BFS) to explore the maze and find a path from start to end.

• Track visited nodes to avoid infinite loops and dead ends.

• Consider edge cases such as multiple paths, loops, and obstacles in the maze.

Class and structure are both used in OOPS concepts, but have different characteristics.

• Classes are reference types while structures are value types

• Classes support inheritance while structures do not

• Classes can have constructors and destructors while structures cannot

• Classes can be used for creating objects while structures are used for storing data

• Examples of classes include String, List, and Dictionary while examples of structures include int, float, and bool

Object-oriented programming concepts include encapsulation, inheritance, and polymorphism.

• Encapsulation: bundling data and methods together in a class

• Inheritance: creating new classes from existing ones, inheriting their properties and behaviors

• Polymorphism: objects of different classes can be treated as objects of a common superclass

• Example: Encapsulation - a class 'Car' with private variables 'make' and 'model', and public methods 'getMake()' and 'setMake()'

• Example: Inherit...read more

Implemented a todo application using React JS

• Used React JS to create components for adding, editing, and deleting tasks

• Implemented state management to keep track of tasks and their completion status

• Utilized local storage or backend server to persist tasks data

• Styled the application using CSS or a CSS framework like Bootstrap

useState is a hook in React that allows functional components to have state.

• useState is used to declare state variables in functional components.

• It returns an array with two values: the current state value and a function to update it.

• The initial state can be passed as an argument to useState.

• Example: const [count, setCount] = useState(0);

NodeJS Event Loop is a mechanism that allows NodeJS to perform non-blocking I/O operations by offloading tasks to the system kernel.

• Event Loop is responsible for handling asynchronous operations in NodeJS.

• It allows NodeJS to perform multiple operations concurrently without blocking the execution.

• Event Loop continuously checks the event queue for any pending tasks and executes them in a non-blocking manner.

• NodeJS uses libuv library to implement the Event Loop.

• Example: When rea...read more

Break a sentence into a list of strings of words

• Use the split() method to break the sentence into an array of strings

• Specify the delimiter to split the sentence by spaces

• Handle punctuation marks and special characters appropriately

To check if a number is prime, iterate from 2 to the square root of the number and check for divisibility.

• Start by checking if the number is less than 2, in which case it is not prime.

• Iterate from 2 to the square root of the number and check if the number is divisible by any of these numbers.

• If the number is divisible by any number in the range, it is not prime. Otherwise, it is prime.

useEffect is a hook in React that allows you to perform side effects in functional components.

• It replaces componentDidMount, componentDidUpdate, and componentWillUnmount.

• It takes two arguments: a function that performs the side effect and an array of dependencies.

• The function is called after every render, unless the dependencies haven't changed.

• Common use cases include fetching data, setting up event listeners, and updating the document title.

The Alien Dictionary Problem is a question that involves sorting words based on a given alien language's alphabetical order.

• The problem can be solved using topological sorting.

• Create a graph where each character is a node and each word is an edge.

• Perform a topological sort on the graph to get the correct order of characters.

• If there is a cycle in the graph, it means the alien language is invalid.

The code I wrote is a function that sorts an array of integers in ascending order using bubble sort algorithm.

• The code starts by iterating through the array and comparing adjacent elements, swapping them if they are in the wrong order.

• This process is repeated until no more swaps are needed, indicating that the array is sorted.

• The time complexity of bubble sort is O(n^2) in the worst case scenario.

• Example: int[] arr = {5, 2, 9, 1, 5}; After sorting: {1, 2, 5, 5, 9}

Use a combination of a stack and a queue to achieve O(1) time complexity for random, push, and pop operations.

• Use a stack to push elements and pop them in O(1) time.

• Use a queue to enqueue elements and dequeue them in O(1) time.

• To achieve random access in O(1) time, maintain an array to store the elements and use a hash map to store the indices of each element.

Bellman Ford Algorithm is a single-source shortest path algorithm that can handle negative edge weights.

• Bellman Ford Algorithm is used to find the shortest path from a single source vertex to all other vertices in a weighted graph.

• It can handle graphs with negative edge weights, unlike Dijkstra's algorithm.

• The algorithm works by relaxing edges repeatedly, updating the shortest path estimates until they converge.

• If there is a negative cycle in the graph, the algorithm can dete...read more

Having clause filters data after grouping, while where clause filters data before grouping.

• Having clause is used with GROUP BY clause to filter data based on aggregate functions.

• Where clause is used to filter data before grouping.

• Having clause cannot be used without GROUP BY clause.

• Where clause can be used with or without GROUP BY clause.

• Having clause is slower than where clause as it filters data after grouping.

• Example: SELECT department, COUNT(*) FROM employees GROUP BY dep...read more

Sort an array of 0s and 1s in O(n) time complexity.

• Use two pointers, one at the beginning and one at the end of the array.

• Swap 0s from the beginning with 1s from the end until the pointers meet.

• Alternatively, count the number of 0s and 1s and overwrite the array with the correct number of each.

Use bitwise shift operators to divide by any number without using / sign

• Use bitwise left shift operator (<<) to multiply the dividend by 2^n where n is the number of times to shift

• Use bitwise right shift operator (>>) to divide the product by 2^n

• Repeat the process until the dividend is less than the divisor

Setup and hold time are timing constraints in digital circuits to ensure proper operation of flip-flops.

• Setup time is the minimum amount of time data must be stable before the clock edge for proper capture.

• Hold time is the minimum amount of time data must be stable after the clock edge for proper capture.

• Violating setup time can lead to metastability issues, while violating hold time can lead to data corruption.

• Example: If setup time is 5ns and hold time is 3ns, data must be ...read more

Find maximum number of intersections in a given time range.

• Consider all the intervals and their start and end times.

• Sort the intervals based on their start times.

• Use a priority queue to keep track of the intervals that are currently active.

• Update the maximum number of intersections whenever a new interval is added or removed from the priority queue.

Event loop is a mechanism in programming that allows for asynchronous execution of code by managing the order of operations.

• Event loop is commonly used in JavaScript to handle asynchronous operations.

• It works by continuously checking the event queue for tasks to execute.

• Tasks are executed in the order they were added to the queue.

• Event loop prevents blocking of the main thread by handling tasks asynchronously.

• Example: setTimeout function in JavaScript uses event loop to execu...read more

The container with most water problem on LeetCode involves finding the maximum area formed by two vertical lines and the x-axis.

• Start with two pointers at the beginning and end of the array.

• Calculate the area between the two pointers and update the maximum area found so far.

• Move the pointer with the smaller height towards the center to potentially find a larger area.

Multithreading allows multiple threads to share the same memory space, while multiprocessing involves separate memory spaces for each process.

• Multithreading is more lightweight and efficient than multiprocessing.

• Multithreading is suitable for tasks that involve I/O operations, while multiprocessing is better for CPU-bound tasks.

• Examples of multithreading include web servers handling multiple requests concurrently, while examples of multiprocessing include running multiple ins...read more

Developed a web application for online shopping with user authentication and payment gateway integration.

• Implemented user registration and login functionality using JWT tokens

• Integrated Stripe API for secure payment processing

• Designed responsive UI using HTML, CSS, and JavaScript

• Utilized Node.js and Express for backend development

The left view of a binary tree is the set of nodes visible when the tree is viewed from the left side.

• Traverse the tree level by level from left to right

• At each level, add the first node encountered to the result array

• Repeat this process for each level of the tree

• Example: For a binary tree with root node 1, left child 2, and right child 3, the left view would be [1, 2]

Code to multiply 2 x 3 matrix

• Create two matrices of size 2x3 and 3x2

• Iterate through rows and columns to perform multiplication

• Store the result in a new matrix of size 2x2

HR policies are guidelines and procedures set by an organization to manage its employees.

• HR policies cover areas such as recruitment, compensation, benefits, performance management, and employee relations.

• They are designed to ensure compliance with legal requirements and promote fairness and consistency in the workplace.

• Examples of HR policies include anti-discrimination policies, code of conduct, and leave policies.

• HR policies are regularly reviewed and updated to reflect ch...read more

Find the maximum sum of a subarray within an array of integers.

• Iterate through the array and keep track of the current sum and maximum sum.

• If the current sum becomes negative, reset it to 0.

• Return the maximum sum found.

Reverse a linked list by changing the next pointers of each node to point to the previous node.

• Start with three pointers: current, previous, and next.

• Iterate through the linked list, updating the next pointer of each node to point to the previous node.

• Update the previous, current, and next pointers for each iteration.

• Example: 1 -> 2 -> 3 -> 4 -> null, after reversing: 4 -> 3 -> 2 -> 1 -> null

DFS (Depth First Search) is a graph traversal algorithm that explores as far as possible along each branch before backtracking.

• DFS is implemented using a stack data structure or recursion.

• It starts at a selected node and explores as far as possible along each branch before backtracking.

• DFS can be used to find connected components, detect cycles, and solve maze problems.

• Example: In a graph with nodes A, B, C, and edges (A, B), (B, C), DFS starting at node A would visit nodes A...read more

Create a SpringBoot application

• Use Spring Initializr to create a new SpringBoot project

• Define a main class with @SpringBootApplication annotation

• Create RESTful APIs using @RestController annotation

• Use Spring Data JPA for database operations

• Implement security using Spring Security

• Handle exceptions using @ControllerAdvice

Deadlocks occur when two or more processes are unable to proceed because each is waiting for the other to release a resource.

• Deadlocks happen in multitasking environments where processes compete for resources.

• Four conditions must hold for a deadlock to occur: mutual exclusion, hold and wait, no preemption, and circular wait.

• Example: Process A holds Resource 1 and waits for Resource 2, while Process B holds Resource 2 and waits for Resource 1.

• Deadlocks can be prevented or reso...read more