60+ Statfinity Interview Questions and Answers

Given an array of words and an integer k, return the k most frequent words sorted by frequency.

• Use a hashmap to count the frequency of each word

• Use a priority queue to keep track of the k most frequent words

• Sort the priority queue based on frequency and lexicographical order

Count the number of structurally unique binary trees that can be constructed with given Dragon Balls.

• Use dynamic programming to solve this problem efficiently.

• The number of structurally unique binary trees can be calculated using Catalan numbers.

• For each test case, calculate the number of structurally unique binary trees modulo 10^9 + 7.

• Return the count of unique binary trees for each test case.

Find the maximum total booked minutes possible in a conference room for given meeting durations with a 15-minute break between meetings.

• Iterate through the list of meeting durations and calculate the maximum total booked minutes by considering the 15-minute break constraint.

• Keep track of the total booked minutes and skip consecutive meetings that violate the break constraint.

• Return the maximum total booked minutes for each test case.

Given an encrypted string with repeated substrings represented by counts, find the K'th character of the decrypted string.

• Parse the encrypted string to extract substrings and their counts

• Iterate through the substrings and counts to build the decrypted string

• Track the position in the decrypted string to find the K'th character

Yes, the quick sort algorithm can be enhanced to achieve NlogN complexity in the worst case by using randomized quick sort or median of three pivot selection.

• Use randomized quick sort to randomly select the pivot element, reducing the chances of worst-case scenarios.

• Implement median of three pivot selection to choose a pivot that is closer to the median value, improving partitioning efficiency.

• Consider using dual pivot quick sort for further optimization in certain cases.

• Exam...read more

The Weighted Job Scheduling problem involves maximizing profit by scheduling non-overlapping jobs with given start times, end times, and profits.

• Sort the jobs by end time in ascending order.

• Initialize an array 'dp' to store maximum profit at each job index.

• For each job, find the latest non-overlapping job and update 'dp' with the maximum profit.

• Return the maximum profit from 'dp'.

Calculate total unique paths from top-left to bottom-right corner of a matrix by moving only right or down.

• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the number of unique paths for each cell.

• Initialize the first row and first column with 1 as there is only one way to reach them.

• For each cell, the number of unique paths is the sum of the paths from the cell above and the cell to the left.

• Return the value in the bottom-right corner of t...read more

The task is to implement a function that reorders edges in a directed acyclic graph to ensure a directed path exists from every node to node 0 with minimum edge reversals.

• Iterate through the graph to find the shortest path from each node to node 0.

• Determine the number of edge reversals needed to create a directed path from each node to node 0.

• Implement a function that performs the edge reversal operation efficiently.

• Consider using graph traversal algorithms like BFS or DFS to...read more

The goal is to schedule jobs to maximize profit while meeting deadlines. Each job takes one unit of time and only one job can be scheduled at a time.

• Sort the jobs in decreasing order of profit

• Iterate through the sorted jobs and schedule them based on their deadlines

• Keep track of the total profit achieved

• Ensure each job is completed before its deadline

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 the starting cell to the last cell.

• Maintain a queue to keep track of the cells to be visited next.

• Consider the effect of snakes and ladders on the movement of the player.

• Handle the boundary conditions and constraints specified in the problem statement.

• Return the minimum number of throws required to reach t...read more

Calculate the intersection point of two lines on a 2D plane with precision up to six decimal places.

• Parse input integers for each test case

• Implement line intersection algorithm

• Handle precision up to six decimal places in output

• Return -1.000000 -1.000000 if lines do not intersect

Determine the minimum number of platforms needed at a railway station so that no train has to wait.

• Sort the arrival and departure times arrays in ascending order.

• Use two pointers to iterate through the arrays and keep track of the number of platforms needed.

• Increment the number of platforms needed when a train arrives and decrement it when a train departs.

• Return the maximum number of platforms needed at any point.

• Example: Input: T = 1, N = 3, AT = [900, 940, 950], DT = [910, ...read more

Given a list of correct spellings and a query string, return a list of suggested correct spellings if the query is misspelled.

• Iterate through the dictionary to check for matching prefixes with the query string.

• If a match is found, add the corresponding word to the list of suggestions.

• Return the list of suggestions if the query is misspelled, otherwise return an empty list.

Implement a function to return the spiral order traversal of a binary tree.

• Traverse the binary tree level by level, alternating between left to right and right to left.

• Use a queue to keep track of nodes at each level.

• Append nodes to the result list in the order they are visited.

Low-level languages interact directly with hardware, while high-level languages are more abstract and easier to read/write.

• Low-level languages are closer to machine code and hardware, while high-level languages are closer to human language.

• Low-level languages require more manual memory management and are less portable, while high-level languages have automatic memory management and are more portable.

• Examples of low-level languages include Assembly and C, while examples of hig...read more

Design a snake game

• Use a 2D array to represent the game board

• Keep track of the snake's position and direction

• Handle user input to change the snake's direction

• Update the snake's position and check for collisions with walls or itself

• Add food to the board and handle eating it to grow the snake

• Keep track of the score and display it to the player

Answering questions on Git, Mercurial, Linux/Windows services, Java thread dump, heap dump, and deadlock

• Git and Mercurial are both version control systems, but Git is more popular and has a steeper learning curve

• Merge conflicts occur when two or more people make changes to the same file at the same time, and can be resolved using tools like Git's merge tool or Mercurial's merge tool

• Starting services in Linux can be done using the systemctl command, while in Windows it can be ...read more

Hypothesis testing in ticket closing example

• Define null and alternative hypothesis

• Choose appropriate statistical test

• Set significance level

• Collect data and calculate test statistic

• Determine p-value and compare with significance level

• Make conclusion and interpret results

I will streamline the process by identifying bottlenecks and implementing automation.

• Analyze current process flow

• Identify areas of delay or inefficiency

• Implement automation tools to reduce manual effort

• Set up clear communication channels between team members

• Track progress and adjust as needed

I prioritize clear communication, seek common ground, and involve all stakeholders in decision-making.

• Open communication with all leads to understand their perspectives

• Identify common goals and areas of agreement

• Involve all stakeholders in decision-making process

• Seek compromise or alternative solutions when necessary

Design a file system to calculate total size and find top k collections in size.

• Create a file system class with methods to add files and calculate total size.

• Maintain a data structure to store the collections and their sizes.

• Implement a method to find the top k collections based on size.

• Consider using a priority queue or sorting the collections based on size.

• Handle edge cases like empty collections or invalid input sizes.

Count characters in a string using array of strings.

• Iterate through each string in the array

• For each string, iterate through each character and increment count

• Return the total count of characters

List all containers with max usage of the special tag 'container'.

• Identify all containers with the special tag 'container'.

• Calculate the usage of each container.

• Find the container(s) with the maximum usage.

Handling customers involves active listening, empathy, problem-solving, and effective communication.

• Listen actively to understand the customer's concerns

• Show empathy and understanding towards the customer's situation

• Offer solutions or alternatives to resolve the issue

• Communicate clearly and effectively to ensure the customer's needs are met

• Follow up to ensure customer satisfaction

Binary search algorithm can be used to find the left and right index of an element in a sorted array.

• Initialize left and right pointers to 0 and length-1 respectively.

• While left <= right, calculate mid index and compare element with array[mid].

• If element is found, update left and right pointers accordingly for left and right index.

• If element is not found, adjust left or right pointer based on comparison with array[mid].

Implement a method to return total usage

• Create a method that calculates the total usage by summing up individual usage values

• Ensure the method can handle different types of usage data (e.g. integers, floats)

• Consider implementing error handling for invalid input data

• Test the method with sample data to verify its accuracy

Create a tic tac toe game with customizable number of boards.

• Accept number of boards as a parameter

• Create a 3x3 grid for each board

• Implement logic to check for winning combinations on each board

Rate limiter is a mechanism to control the rate of requests sent to a server

• Implement a sliding window algorithm to track the number of requests within a specific time frame

• Set a limit on the number of requests allowed per unit of time

• Return an error response when the limit is exceeded

• Test cases: 1. Send requests below the limit - should be successful. 2. Send requests above the limit - should receive an error response.

Rate limiter design using token bucket algorithm

• Use token bucket algorithm to limit the rate of requests

• Maintain a bucket with tokens that get refilled at a constant rate

• Each request consumes a token from the bucket, rejecting requests when no tokens are available

Atlassian values are centered around teamwork, openness, and customer focus.

• Atlassian values collaboration and encourages employees to work together to achieve common goals.

• Openness is a key value, with transparency and honesty being highly valued.

• Customer focus is a top priority, with a commitment to delivering high-quality products and services that meet customer needs.

• Other values include innovation, continuous improvement, and a focus on results.

• Examples of Atlassian valu...read more

To resolve a DNS query, you can use various methods such as checking the DNS cache, querying authoritative DNS servers, and troubleshooting network connectivity.

• Check the local DNS cache for a matching entry

• Query the recursive DNS server configured on the device

• If the recursive server doesn't have the answer, it queries authoritative DNS servers

• Troubleshoot network connectivity issues if DNS resolution fails

IRR stands for Internal Rate of Return, a financial metric used to evaluate the profitability of an investment.

• IRR is a discount rate that makes the net present value of all cash flows from an investment equal to zero.

• It is used to compare the profitability of different investment opportunities.

• A higher IRR indicates a more profitable investment.

• For example, if an investment has an IRR of 10%, it means that the investment is expected to generate a return of 10% per year.

Project success can be measured by meeting project goals, staying within budget and timeline, and receiving positive feedback from stakeholders.

• Meeting project goals and objectives

• Staying within budget and timeline

• Receiving positive feedback from stakeholders

• Achieving desired outcomes and deliverables

• Maintaining high team morale and engagement

Feature selection can be done using techniques like filter methods, wrapper methods, and embedded methods.

• Filter methods involve selecting features based on statistical measures like correlation, chi-squared test, etc.

• Wrapper methods use a specific machine learning algorithm to evaluate the importance of features through iterative selection.

• Embedded methods incorporate feature selection within the model training process, like Lasso regression for sparse feature selection.

• Exam...read more

Design a classic Snake game based on Nokia phones.

• Use a 2D array to represent the game board.

• Implement logic for snake movement and growth.

• Include collision detection with walls and itself.

• Add food items for the snake to eat and grow.

• Display the game on a grid-based interface.

Train a Decision Tree based on provided dataset.

• Preprocess the dataset by handling missing values and encoding categorical variables.

• Split the dataset into training and testing sets.

• Train the Decision Tree model on the training set.

• Evaluate the model's performance on the testing set using metrics like accuracy or F1 score.

Rate limiting is a technique used to control the number of requests or actions a user or system can perform within a certain time frame.

• Rate limiting helps prevent abuse, protect resources, and ensure fair usage.

• It sets limits on the number of requests or actions allowed per user, IP address, or API key.

• Rate limits can be defined based on time intervals, such as requests per second, minute, or hour.

• When the limit is reached, further requests may be denied, delayed, or throttl...read more

Encapsulation is the concept of bundling data and methods that operate on the data into a single unit, known as a class.

• Encapsulation helps in hiding the internal state of an object and restricting access to it.

• It allows for better control over the data by preventing direct modification from outside the class.

• Access to the data is provided through methods, which can enforce validation rules and ensure data integrity.

• Example: In a class representing a bank account, the balance...read more

I have extensive experience in creating solution designs at my current job.

• I have led multiple cross-functional teams to develop innovative solutions

• I have a strong background in analyzing requirements and translating them into technical designs

• I have successfully implemented various solutions to improve efficiency and productivity

• I have experience in presenting and defending solution designs to stakeholders

JVM stands for Java Virtual Machine, which is a virtual machine that enables a computer to run Java programs. JDK stands for Java Development Kit, which is a software development kit used to develop Java applications.

• JVM is responsible for executing Java bytecode and translating it into machine code.

• JDK includes tools for developing, debugging, and monitoring Java applications.

• JDK contains JRE (Java Runtime Environment) which includes JVM, libraries, and other necessary compo...read more

Strong consistency ensures that all replicas of data are updated synchronously, while eventual consistency allows for temporary inconsistencies.

• Strong consistency guarantees that all clients see the same data at the same time.

• Eventual consistency allows for temporary inconsistencies but eventually all replicas will converge to the same state.

• Strong consistency is often used in systems where data integrity is critical, such as financial transactions.

• Eventual consistency is com...read more

Calculating the size of a file system

• Determine the total size of all files and directories within the file system

• Include the size of all subdirectories and their contents

• Consider the size of metadata and file system overhead

• Use appropriate tools or commands to gather the necessary information

Inheritance is a mechanism in object-oriented programming where a class inherits properties and behaviors from another class.

• Allows a class to inherit attributes and methods from another class

• Promotes code reusability and reduces redundancy

• Creates a parent-child relationship between classes

• Example: Class 'Car' can inherit from class 'Vehicle' and inherit properties like 'speed' and methods like 'drive()'

Polymorphism is the ability of a single function or method to operate on different types of data.

• 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: Animal superclass with Dog and Cat subclasses. Both Dog and Cat can be treated as Animals.

Abstraction is the concept of hiding complex implementation details and showing only the necessary features to the user.

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

• It helps in reducing complexity and improving code readability

• Example: In Java, abstract classes and interfaces are used to achieve abstraction

DFS and BFS are fundamental graph traversal algorithms used to explore nodes in a graph.

• DFS (Depth First Search) explores as far as possible along each branch before backtracking. It uses a stack to keep track of nodes.

• BFS (Breadth First Search) explores all the neighbor nodes at the present depth prior to moving on to the nodes at the next depth. It uses a queue to keep track of nodes.

• Example: For a graph with nodes A, B, C, D and edges (A, B), (A, C), (B, D), DFS would visi...read more

Feature flag component to control feature toggling in the application

• Create a component that accepts a feature flag name as prop

• Check if the feature flag is enabled or disabled

• Render the component content based on the feature flag status

Heap memory is a region of a computer's memory that is used for dynamic memory allocation.

• Heap memory is allocated at runtime and can be accessed randomly.

• It is used for storing objects and data structures that need to be dynamically allocated and deallocated.

• Heap memory is managed by the programmer and not automatically by the system.

• Examples of heap memory usage include creating objects in Java using the 'new' keyword or allocating memory using malloc() in C.

Our culture is collaborative, innovative, and inclusive.

• We prioritize teamwork and encourage open communication.

• We value creativity and encourage employees to share their ideas.

• We strive to create a welcoming and diverse environment for all employees.

• We prioritize work-life balance and offer flexible schedules and remote work options.

• We prioritize professional development and offer opportunities for growth and learning.

An update query in SQL is used to modify existing records in a database.

• Use the UPDATE keyword followed by the table name

• Set the column(s) to be updated using SET

• Specify the new values for the columns

• Add a WHERE clause to specify which records to update

The question is asking to find the top k collections.

• Use a sorting algorithm to sort the collections in descending order based on a specific criteria.

• Select the top k collections from the sorted list.

• Return the selected collections as an array of strings.

Find the longest increasing subsequence in an array

• Use dynamic programming to solve this problem

• Iterate through the array and keep track of the longest increasing subsequence ending at each index

• Time complexity can be optimized to O(n log n) using binary search

Values are principles or beliefs that guide behavior and decision-making.

• Values can include honesty, integrity, respect, and teamwork.

• An example of values in action is a company prioritizing transparency in communication with employees.

• Another example is an individual choosing to speak up against unethical behavior in the workplace.

• Values can also be demonstrated through actions such as volunteering in the community or supporting diversity and inclusion initiatives.

Snake game involves controlling a snake to eat food and grow in size without hitting walls or itself.

• Create a grid system to represent the game board

• Implement logic for snake movement and growth

• Generate food randomly on the board for the snake to eat

• Handle collision detection for walls and snake body

• Keep track of score and game over conditions

Design a system for tagging system

• Consider scalability and performance requirements

• Use a unique identifier for each tag

• Implement a search functionality for tags

• Ensure data consistency and integrity

• Consider security measures to prevent unauthorized access

Calculate the total size of an array of strings.

• Iterate through the array and sum the length of each string.

• Use the `length` property of each string to get its size.

• Handle edge cases such as empty strings or null values.

REST API is important for enabling communication between different systems and allowing them to exchange data and functionality.

• REST API allows systems to communicate and exchange data in a standardized and scalable manner.

• It enables integration between different applications and platforms, facilitating interoperability.

• REST API simplifies the development process by providing a uniform interface for accessing and manipulating resources.

• It promotes loose coupling between syste...read more

Troubleshooting with Har file involves analyzing network traffic and identifying issues.

• Use a tool like Chrome Developer Tools or Fiddler to generate a Har file

• Open the Har file in a Har viewer to analyze the network requests and responses

• Look for errors, slow response times, or missing resources

• Check for DNS resolution issues, network connectivity problems, or server-side errors

• Compare the Har file with expected behavior or known good requests

• Use the information from the Har...read more

Design a tagging system for organizing and categorizing data.

• Consider the types of data to be tagged (e.g. text, images, videos)

• Create a standardized set of tags and categories

• Allow for multiple tags to be assigned to each piece of data

• Implement a search function based on tags

• Consider implementing a hierarchy of tags for more complex categorization

Snake game is a classic arcade game where a player controls a snake to eat food and grow longer while avoiding collisions with walls and itself.

• Create a grid-based game board where the snake can move in four directions (up, down, left, right)

• Generate food randomly on the board for the snake to eat and grow in length

• Implement collision detection to check if the snake hits the walls or itself

• Update the game state continuously based on user input and game logic

• Keep track of the ...read more

Design a web crawler to fetch and index web pages

• Start by defining the scope of the crawler (e.g. which websites to crawl)

• Implement a system to fetch web pages using HTTP requests

• Parse the HTML content to extract relevant information (e.g. links, text)

• Store the extracted data in a database or index for later retrieval

• Implement a scheduling mechanism to prioritize and manage the crawling process