60+ SDE Intern Interview Questions and Answers

Count the occurrences of each character in a given string including special characters.

• Create test cases for empty string

• Test for string with only one character

• Test for string with all characters being the same

• Test for string with all characters being different

• Test for string with special characters

Find square root of a number using basic arithmetic operations without power operator and inbuilt libraries.

• Use binary search to find the integer part of the square root

• Use long division method to find the decimal part of the square root

• Repeat the above steps until desired accuracy is achieved

• Handle edge cases like negative numbers and numbers less than 1

Designing an e-commerce web app involves user interface, product management, payment processing, and scalability considerations.

• User Interface: Create a responsive design for easy navigation and product discovery.

• Product Management: Implement a database to manage product listings, including categories, descriptions, and images.

• User Authentication: Allow users to create accounts, log in, and manage their profiles.

• Shopping Cart: Enable users to add products to a cart and manage...read more

Remove duplicate characters from a string while preserving order.

• Create an empty string to hold the result.

• Iterate through each character in the input string.

• If the character is not already in the result string, add it.

• Return the result string.

Given a Y-linked list, find the node at the intersection point.

• Traverse both branches of the Y-linked list and compare nodes.

• Use a hash table to store visited nodes and check for intersection.

• If one branch is longer, traverse it until it matches the length of the other branch.

To change permissions for a file, you can use the chmod command in the terminal.

• Use the chmod command followed by the permission code and the file name

• Permission codes include 'u' for user, 'g' for group, and 'o' for others, along with 'r' for read, 'w' for write, and 'x' for execute

• For example, to give read and write permissions to the user for a file named 'example.txt', you can use 'chmod u+rw example.txt'

Traverse a binary tree in spiral order, alternating between left-to-right and right-to-left at each level.

• Use two stacks: one for the current level and one for the next level.

• Start with the root node in the first stack.

• While there are nodes in the current stack, pop nodes and add their children to the next stack in the opposite order.

• Switch stacks after each level to alternate the traversal direction.

• Example: For a tree with root 1, left child 2, right child 3, the spiral ord...read more

Using React.js to fetch and display data from an API involves state management and lifecycle methods.

• Use the useEffect hook to fetch data when the component mounts.

• Utilize the useState hook to manage the fetched data.

• Handle loading and error states to improve user experience.

• Example: Fetching user data from an API and displaying it in a list.

• Consider using async/await for cleaner asynchronous code.

A load balancer distributes network traffic across multiple servers to ensure reliability and optimize resource use.

• Improves application availability by distributing requests to multiple servers.

• Can be hardware-based (like F5) or software-based (like Nginx).

• Helps in scaling applications by adding more servers as demand increases.

• Supports various algorithms like Round Robin, Least Connections, and IP Hash.

• Example: A website using a load balancer can handle more users by spread...read more

Remove duplicates from a sorted linked list

• Use two pointers - one to iterate through the list and another to keep track of unique elements

• Compare current node with next node, if they are equal, skip the next node

• Repeat until end of list is reached

Find the lowest common ancestor (LCA) of two nodes in a binary search tree (BST) efficiently.

• In a BST, for any node, left children are smaller and right children are larger.

• To find LCA of nodes p and q, start from the root.

• If both p and q are smaller than the root, LCA lies in the left subtree.

• If both p and q are larger than the root, LCA lies in the right subtree.

• If one is on the left and the other is on the right, the root is the LCA.

• Example: For nodes 2 and 8 in a BST, if ...read more

Addition of two linked lists and return the result as a linked list.

• Traverse both linked lists simultaneously

• Add corresponding nodes and carry over the sum

• Create a new linked list with the sum

I have worked on various projects using different tech stacks including Java, Python, and JavaScript.

• Developed a web application using Java Spring Boot framework

• Created a data analysis tool using Python libraries such as Pandas and NumPy

• Built a real-time chat application using JavaScript and Node.js

• Implemented machine learning algorithms using Python's scikit-learn library

• Worked on a mobile application using React Native framework

SQL query to manage pick and drop of passengers in a transport system

• Create a table for passengers with columns like passenger_id, name, pick_up_location, drop_off_location, etc.

• Create a table for transport vehicles with columns like vehicle_id, driver_name, capacity, etc.

• Use JOIN to link the two tables based on pick_up_location and drop_off_location.

• Consider adding a table for routes and scheduling for better organization.

• Example: SELECT * FROM passengers p JOIN vehicles v O...read more

React key concepts include Props, State, and Hooks, essential for building dynamic user interfaces.

• Props: Short for properties, used to pass data from parent to child components. Example: <ChildComponent name='John' />.

• State: A component's internal data storage that can change over time. Example: const [count, setCount] = useState(0);.

• Hooks: Functions that let you use state and other React features in functional components. Example: useEffect(() => { /* side effects */ }, [])...read more

Find the next permutation of a given timestamp in HH:MM AM/PM format.

• Convert the timestamp to a 24-hour format for easier manipulation.

• Identify the rightmost pair where the earlier digit is smaller than the later one.

• Swap this digit with the smallest larger digit to its right.

• Reverse the digits to the right of the swapped position to get the next permutation.

• Example: For '11:55 PM', the next permutation is '12:00 AM'.

Multithreading is not natively supported in JavaScript, but can be achieved through Web Workers.

• JavaScript is a single-threaded language, meaning it can only execute one task at a time.

• Web Workers allow for multithreading in JavaScript by running scripts in the background.

• Web Workers can communicate with the main thread using message passing.

• Examples of tasks that can benefit from multithreading include heavy computations and long-running processes.

Meta is a leading company in AI space with a focus on developing innovative technologies and solutions.

• Meta (formerly Facebook) is known for its advanced AI research and development.

• Meta uses AI for various applications such as content moderation, personalized recommendations, and virtual assistants.

• Meta's AI technologies power products like facial recognition, language translation, and image recognition.

Find the missing number in an array containing numbers from 1 to n.

• Iterate through the array and calculate the sum of all numbers from 1 to n.

• Calculate the sum of all numbers in the given array.

• Subtract the sum of array from the sum of all numbers to find the missing number.

The Node.js event loop manages asynchronous operations, allowing non-blocking execution of code in a single-threaded environment.

• The event loop is a core part of Node.js that handles asynchronous callbacks.

• It operates in phases: timers, I/O callbacks, idle, poll, check, and close callbacks.

• Example: setTimeout() schedules a callback to run after a specified delay.

• I/O operations (like reading files) are offloaded to the system, allowing the event loop to continue processing oth...read more

Find leaf nodes in a binary tree and print path to each leaf node.

• Traverse the binary tree using depth-first search (DFS)

• When reaching a leaf node, store the path from root to that leaf node

• Repeat the process for all leaf nodes in the tree

Function to insert, delete, and print a linked list

• Create a Node class with data and next pointer

• Implement insert function to add a new node at the end of the linked list

• Implement delete function to remove a node by value

• Implement print function to display all elements in the linked list

Find the deepest left node in a binary tree.

• Traverse the tree recursively and keep track of the depth and whether the current node is a left node.

• If the current node is a leaf node and its depth is greater than the deepest left node found so far, update the deepest left node.

• Return the deepest left node found.

• Example: For the binary tree with root node 1, left child 2, and left child of 2 being 4, the deepest left node is 4.

• Example: For the binary tree with root node 1, left ...read more

Optimizing code and estimating time complexity

• Identify bottlenecks in the code and optimize them

• Use efficient data structures and algorithms

• Analyze the code to determine its time complexity

• Consider worst-case, best-case, and average-case scenarios

• Use Big O notation to express the time complexity

Use binary search to efficiently search for an element in a sorted matrix.

• Start from the top right corner of the matrix

• If the target is greater than the current element, move down

• If the target is less than the current element, move left

• Repeat until the target is found or all elements are checked

Virtual DOM is a lightweight copy of the actual DOM used for efficient updates.

• Virtual DOM is a concept used in modern web development frameworks like React.

• It is a lightweight copy of the actual DOM that is used to track changes and update the actual DOM efficiently.

• When a change is made to the virtual DOM, it is compared with the previous version to identify the minimum number of changes required to update the actual DOM.

• This approach reduces the number of updates required ...read more

Single way binding updates the view when the model changes, while two way binding updates both the view and the model.

• Single way binding updates the view when the model changes, but not vice versa.

• Two way binding updates both the view and the model when either changes.

• Single way binding is commonly used in frameworks like AngularJS, while two way binding is used in frameworks like Vue.js.