70+ Fullstack Developer Intern Interview Questions and Answers

Implement a function to find the shortest path in an unweighted graph from house 'S' to house 'T'.

• Use Breadth First Search (BFS) algorithm to find the shortest path in an unweighted graph.

• Create a queue to store the current house and its neighbors, and a visited set to keep track of visited houses.

• Start BFS from house 'S' and stop when reaching house 'T'.

• Return the path from 'S' to 'T' once 'T' is reached.

• If multiple shortest paths exist, any one can be returned.

• Example: For ...read more

Dijkstra's algorithm is used to find the shortest path from a source node to all other nodes in a graph with weighted edges.

• Implement Dijkstra's algorithm to find the shortest path distances from the source node to all other nodes

• Use a priority queue to efficiently select the next node with the shortest distance

• Update the distances of neighboring nodes if a shorter path is found

• Handle disconnected vertices by assigning a large value (e.g., 2147483647) as the distance

• Ensure no...read more

The task is to find the length of the longest common subsequence between two given strings.

• Implement a function to find the longest common subsequence between two strings.

• Use dynamic programming to solve the problem efficiently.

• Iterate through the strings and build a matrix to store the lengths of common subsequences.

• Return the length of the longest common subsequence.

• Example: For input STR1 = 'abcde' and STR2 = 'ace', the longest common subsequence is 'ace' with a length of ...read more

Find the second most repeated word in an array of strings with unique frequencies.

• Iterate through the array and count the frequency of each word using a hashmap.

• Sort the hashmap by frequency in descending order.

• Return the second key in the sorted hashmap.

Given a special keyboard with four keys, determine the maximum number of 'A's that can be printed on the screen by pressing the keys 'N' times.

• Use dynamic programming to keep track of the maximum number of 'A's that can be printed at each step.

• At each step, consider the possibilities of pressing 'A', 'Ctrl-A', 'Ctrl-C', and 'Ctrl-V'.

• Optimally choose the sequence of keys to maximize the number of 'A's printed on the screen.

• Example: For N = 7, the optimal sequence is: A, A, A, ...read more

The N Queens Problem involves finding all possible placements of N queens on an N x N chessboard where no two queens threaten each other.

• Use backtracking algorithm to explore all possible configurations.

• Keep track of rows, columns, and diagonals to ensure queens do not threaten each other.

• Generate all valid configurations and print them out.

• Consider edge cases like N = 1 or N = 2 where no valid configurations exist.

Find the minimum number of dice throws required to reach the last cell on a 'Snake and Ladder' board.

• Use Breadth First Search (BFS) algorithm to find the shortest path from start to end cell.

• Create a mapping of each cell to its corresponding row and column on the board.

• Consider the special cases of snakes and ladders while calculating the next possible moves.

• Keep track of visited cells to avoid revisiting them during the traversal.

Print strings with at least one digit from given array.

• Iterate through each string in the array and check if it contains a digit using regular expressions.

• Use the regex pattern '\d' to match any digit in a string.

• Print the strings that match the pattern.

Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope.

• Hoisting applies to variable declarations and function declarations

• Variables are initialized with undefined and functions are fully defined

• Hoisting only moves the declarations, not the assignments

• Example: console.log(x); var x = 5; // Output: undefined

• Closure is a function that has access to its outer function's variables, even after the outer function has returned...read more

This could refer to anything in javascript, please provide more context.

• Please provide more context for a specific answer.

• It could be a variable, function, object, or any other javascript construct.

• Without more information, it is impossible to provide a specific answer.

Find pairs in an array that sum to a specific value, like 6, using efficient algorithms.

• Use a hash set to store elements as you iterate through the array.

• For each element, check if (target - element) exists in the set.

• Example: For array [1, 2, 3, 4, 5], pairs are (1, 5), (2, 4).

• Time complexity is O(n) due to single pass through the array.

NodeJS is a runtime environment for executing JavaScript code outside of a web browser.

• NodeJS allows JavaScript to be run on the server-side, enabling backend development.

• NodeJS has a built-in library of modules that can be easily integrated into applications.

• NodeJS is event-driven and non-blocking, making it efficient for handling multiple requests simultaneously.

Box model is a way of representing HTML elements as rectangular boxes with content, padding, border, and margin.

• The box model consists of content, padding, border, and margin.

• Content is the actual content of the element.

• Padding is the space between the content and the border.

• Border is the line that surrounds the padding and content.

• Margin is the space between the border and other elements.

• To center an input tag, set margin-left and margin-right to auto and display to block.

The sum of the series n/1, n/2, n/3, ..., n/m is calculated and printed.

• Iterate from 1 to m and calculate n divided by the current number in the iteration.

• Add all the calculated values to get the sum of the series.

• Print the final sum of the series.

Integrate AI by identifying use cases, selecting appropriate models, and implementing them in the product's architecture.

• Identify specific use cases for AI, such as predictive analytics or personalized recommendations.

• Choose the right AI models based on the use case, e.g., using NLP for chatbots or image recognition for medical imaging.

• Integrate AI models into the existing tech stack, ensuring compatibility with backend services and databases.

• Utilize cloud services like AWS o...read more

Explanation of sorting techniques and implementation of bubble sort

• Sorting techniques include bubble sort, selection sort, insertion sort, merge sort, quick sort, etc.

• Bubble sort compares adjacent elements and swaps them if they are in the wrong order, repeating until the array is sorted.

• Example: [5, 3, 8, 2, 1] -> [3, 5, 8, 2, 1] -> [3, 5, 2, 8, 1] -> [3, 5, 2, 1, 8] -> [3, 2, 5, 1, 8] -> [3, 2, 1, 5, 8] -> [2, 3, 1, 5, 8] -> [2, 1, 3, 5, 8] -> [1, 2, 3, 5, 8]

Typing a URL initiates a series of steps to retrieve and display the requested web page in the browser.

• The browser checks the cache for the URL to see if the page is stored locally.

• If not cached, the browser performs a DNS lookup to resolve the domain name to an IP address.

• The browser establishes a TCP connection to the server using the resolved IP address.

• An HTTP request is sent to the server to fetch the requested resource (e.g., HTML, CSS, JS).

• The server processes the requ...read more

No, databases cannot be stored using only POST requests.

• Databases are typically stored on a server or in the cloud, not through HTTP requests.

• POST requests are used to send data to a server, not to store databases.

• Database management systems like MySQL, PostgreSQL, or MongoDB are used to store and manage databases.

Angular is a platform for building web applications using TypeScript, components, and a powerful dependency injection system.

• Angular uses a component-based architecture, where each component encapsulates its own view and logic.

• Data binding in Angular allows for automatic synchronization between the model and the view, using syntax like {{}} for interpolation.

• Angular's dependency injection system helps manage service instances and promotes modularity and testability.

• The Angula...read more

I have worked on various projects, including a personal portfolio site and a collaborative web application for task management.

• Developed a personal portfolio website using React and CSS to showcase my projects and skills.

• Collaborated on a task management web app using Node.js and Express, implementing user authentication and real-time updates.

• Created a simple e-commerce site with a shopping cart feature using HTML, CSS, and JavaScript.

• Built a weather application using APIs to...read more

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

• useState is a built-in hook in React.

• It allows functional components to have state variables.

• It takes an initial state value and returns an array with the current state value and a function to update it.

• The state can be updated using the function returned by useState.

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

Temporal dead zone is a behavior in JavaScript where a variable cannot be accessed before it is declared.

• Variables declared with let and const are hoisted but cannot be accessed before their declaration

• Trying to access a variable in its temporal dead zone results in a ReferenceError

• Temporal dead zone is a feature introduced in ES6 to improve JavaScript's scoping mechanism

Debugging is the systematic process of identifying, isolating, and fixing bugs in software code.

• Identify the bug: Use error messages or unexpected behavior to pinpoint the issue.

• Reproduce the issue: Create a test case that consistently triggers the bug.

• Isolate the cause: Use debugging tools or print statements to narrow down the source of the problem.

• Fix the bug: Modify the code to resolve the issue, ensuring it doesn't introduce new bugs.

• Test the fix: Run tests to confirm th...read more

I developed a PHP-based web application for managing a local library's inventory and user accounts.

• Created a user-friendly interface for librarians to add, update, and delete book records.

• Implemented user authentication allowing patrons to create accounts and borrow books.

• Utilized MySQL for database management to store book details and user information.

• Integrated search functionality to help users find books by title, author, or genre.

• Developed an admin dashboard for monitori...read more

Discussing design choices in problem-solving for a Fullstack Developer Intern role.

• Prioritize user experience: Ensure the interface is intuitive and easy to navigate, e.g., using consistent button styles.

• Choose appropriate tech stack: Select frameworks and languages that align with project requirements, e.g., React for frontend and Node.js for backend.

• Implement responsive design: Ensure the application works well on various devices, e.g., using CSS Grid or Flexbox.

• Optimize pe...read more

Creating a fullstack authentication system with signup and signin forms for users.

• Frontend: Use React for building the UI components for signup and signin forms.

• Backend: Use Node.js with Express to handle API requests for authentication.

• Database: Use MongoDB to store user credentials securely.

• Signup Form: Include fields for email, password, and confirm password.

• Signin Form: Include fields for email and password.

• Validation: Implement client-side validation for form inputs.

• Hash...read more

Data types in JavaScript include primitive and object types.

• Primitive types include string, number, boolean, null, undefined, and symbol.

• Object types include arrays, functions, and objects.

• Typeof operator can be used to determine the type of a variable.

• Type coercion can occur when different types are used together.

Transactions in SQL are a way to ensure data integrity by grouping multiple SQL statements into a single unit of work.

• Transactions help maintain the ACID properties of a database (Atomicity, Consistency, Isolation, Durability).

• They allow multiple SQL statements to be executed as a single unit, either all succeeding or all failing.

• Limits in SQL refer to constraints set on the amount of data that can be stored or processed in a database table or query result.

• Examples of limits ...read more