40+ Pushpinder Singh Sidhu Contractor Interview Questions and Answers

Sort an array of 0s and 1s in linear time without using additional arrays.

• Iterate through the array and maintain two pointers, one for 0s and one for 1s.

• Swap elements at the two pointers based on the current element being 0 or 1.

• Continue this process until the entire array is sorted in place.

Find the number with the maximum frequency in an array of integers.

• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Find the number with the maximum frequency and return it.

• If multiple elements have the same maximum frequency, return the one that appears first.

Find the maximum sum of any contiguous subarray within an array of integers.

• Iterate through the array and keep track of the maximum sum of subarrays encountered so far.

• At each index, decide whether to include the current element in the subarray or start a new subarray.

• Update the maximum sum if a new maximum is found.

• Example: For array [34, -50, 42, 14, -5, 86], the maximum sum is 137.

• Example: For array [-5, -1, -8, -9], the maximum sum is -1.

Reverse a singly linked list of integers and return the head of the reversed linked list.

• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Use three pointers to keep track of the current, previous, and next nodes while reversing the linked list.

• Update the head of the reversed linked list as the last node encountered during the reversal process.

Find the shortest path in a binary matrix from a source cell to a destination cell consisting only of 1s.

• Use Breadth First Search (BFS) to explore all possible paths from the source cell to the destination cell.

• Keep track of visited cells to avoid revisiting them.

• Update the path length as you traverse through the matrix.

• Return the shortest path length found or -1 if no valid path exists.

Given an array representing an elevation map, find the maximum amount of rainwater that can be trapped between the bars.

• Iterate through the array and calculate the maximum height on the left and right of each bar.

• Calculate the trapped water by finding the minimum of the maximum heights on the left and right minus the current bar height.

• Sum up the trapped water for all bars to get the total trapped rainwater.

• Example: For input [0, 1, 0, 2], the trapped rainwater is 1 unit.

• Exam...read more

The task is to determine the maximum profit that can be achieved by performing up to two buy-and-sell transactions on a given set of stock prices.

• Iterate through the array of stock prices to find the maximum profit that can be achieved by buying and selling stocks.

• Keep track of the maximum profit that can be obtained by performing two transactions.

• Consider all possible combinations of buying and selling stocks to maximize profit.

• Ensure to sell the stock before buying again to...read more

Determine if Ninja can reach his friend's house with even x-coordinate without using modulus operator.

• Check if the x-coordinate is even or odd by using bitwise AND operation with 1.

• Return 1 if x-coordinate is even, else return 0.

• Handle multiple test cases by iterating through each input.

Find the length of the longest substring with at most K distinct characters in a given string.

• Use a sliding window approach to keep track of the characters and their counts within the window.

• Maintain a hashmap to store the characters and their frequencies.

• Update the window size and characters count as you iterate through the string.

• Return the maximum window size encountered for each test case.

Implement a function to check if a given integer is a perfect square.

• Create a function that takes an integer as input and returns true if it is a perfect square, false otherwise.

• Iterate through possible square roots of the input integer and check if the square of the root equals the input.

• Return true if a perfect square is found, false otherwise.

The task is to print the bottom view of a binary tree from left to right.

• Traverse the binary tree in level order and keep track of the horizontal distance of each node from the root.

• Store the nodes at each horizontal distance in a map, updating it as you traverse the tree.

• After traversal, extract the bottom-most nodes at each horizontal distance to get the bottom view sequence.

Implement functions to calculate mean, median, and mode of an integer array.

• Calculate mean by summing all elements and dividing by total count

• Calculate median by sorting array and finding middle element(s)

• Calculate mode by finding element with highest frequency, return smallest if multiple

Find the K-th smallest element in an array of distinct integers.

• Sort the array and return the element at index K-1.

• Use a min-heap to find the K-th smallest element efficiently.

• Implement quickselect algorithm for optimal performance.

The task is to find all distinct triplets in an array that sum up to a specified number.

• Iterate through all possible triplets using three nested loops.

• Check if the sum of the triplet equals the target sum.

• Print the triplet if found, else print -1.

Find duplicates in an array of integers within a specified range.

• Iterate through the array and keep track of the count of each element using a hashmap.

• Return elements with count greater than 1 as duplicates.

• Time complexity can be optimized to O(N) using a set to store seen elements.

Implement Merge Sort algorithm to sort a given sequence of numbers in non-descending order.

• Merge Sort is a divide-and-conquer algorithm that splits the array into two halves, recursively sorts each half, and then merges the sorted halves back together.

• Time complexity of Merge Sort is O(n log n) in the worst case scenario.

• It is a stable sorting algorithm, meaning that the relative order of equal elements is preserved.

• Example: Input: [5, 3, 8, 6, 2], Output: [2, 3, 5, 6, 8]

Find the maximum sum of a subset of an array that does not exceed a given value K.

• Sort the array in descending order to maximize the sum.

• Iterate through the array and add elements to the sum until it exceeds K.

• Return the sum obtained before exceeding K.

Create a grid pattern with diamond shapes of given size in each cell.

• Iterate through each cell in the grid and construct the diamond shape based on the size provided.

• Use 'e' for the outer space, '/' and '' for the borders, 'o' for the inner space of the diamond.

• Adjust the positioning of characters based on the size of the diamond to create the desired pattern.

Implementing cart functionality in an e-commerce application involves managing user interactions, updating quantities, handling discounts, and processing orders.

• Create a data structure to store cart items, quantities, and prices.

• Implement add to cart, remove from cart, and update quantity functionalities.

• Handle discounts, promotions, and coupon codes.

• Calculate total price, including taxes and shipping costs.

• Implement checkout process to place orders and update inventory.

• Consi...read more

Implement multiple RecyclerViews on a magnified screen in an Android app by adjusting item sizes and spacing.

• Adjust item sizes and spacing based on screen magnification level

• Use nested RecyclerViews or custom layouts to display multiple lists

• Implement custom item decorators to manage spacing between RecyclerViews

• Consider using a GridLayoutManager with custom span sizes for each RecyclerView

To collect NPA payment when customer contact is missing, utilize various methods such as skip tracing, contacting references, using social media, and legal actions if necessary.

• Perform skip tracing to locate the customer's current contact information.

• Contact references provided by the customer to gather any updated contact details.

• Utilize social media platforms to search for the customer and attempt to establish contact.

• Send written communication to the customer's last known ...read more

Design a system to handle 10 lacs transactions per second.

• Use distributed systems and load balancing to handle the high volume of transactions.

• Implement caching mechanisms to reduce database load.

• Use high-performance hardware and optimize code for speed.

• Consider using a NoSQL database for faster read/write operations.

• Implement fault-tolerant mechanisms to ensure system reliability.

• Use asynchronous processing to handle requests quickly.

• Consider using a message queue to handle ...read more

To exploit/test for vulnerabilities, use penetration testing tools and techniques to simulate attacks and identify weaknesses.

• Use vulnerability scanners to identify potential vulnerabilities

• Conduct penetration testing to simulate attacks and identify weaknesses

• Perform social engineering tests to assess human vulnerabilities

• Use fuzzing techniques to identify software vulnerabilities

• Conduct code reviews to identify potential vulnerabilities

• Test for security misconfigurations

• Use...read more

Create a custom hashmap with OOPs concepts

• Create a class for the hashmap with private variables for key and value

• Implement methods for adding, removing and retrieving elements

• Use inheritance to create a separate class for each type of data to be stored

• Use encapsulation to protect the data and ensure proper access

• Use polymorphism to allow for different types of data to be stored in the same hashmap

The bridge between SwiftUI and UIKit is represented by the UIViewRepresentable and UIViewControllerRepresentable protocols.

• UIViewRepresentable and UIViewControllerRepresentable protocols allow SwiftUI views to interact with UIKit views and controllers respectively.

• UIViewRepresentable is used to wrap a UIKit view and make it available to SwiftUI.

• UIViewControllerRepresentable is used to wrap a UIKit view controller and make it available to SwiftUI.

• These protocols enable develop...read more

Explain the importance of paying the amount and address any concerns the customer may have.

• Explain the reasons for the amount owed (e.g. services provided, products purchased)

• Discuss the consequences of not paying the amount (e.g. late fees, credit score impact)

• Offer solutions or payment plans to help the customer meet their financial obligations

• Listen to the customer's concerns and try to find a mutually beneficial resolution

I implement training programs, provide resources, set clear goals, and offer regular feedback to enhance caller productivity.

• Implementing training programs to improve skills and knowledge

• Providing resources such as tools and technology to streamline processes

• Setting clear goals and expectations for callers to work towards

• Offering regular feedback and coaching to help callers improve performance

Designing a Google Search Engine involves creating a web crawler, indexing system, and ranking algorithm.

• Develop a web crawler to discover and retrieve web pages.

• Implement an indexing system to store and organize the content of web pages.

• Design a ranking algorithm to determine the relevance of search results.

• Include features like autocomplete, spell check, and personalized search results.

• Optimize for speed and scalability to handle large amounts of data and user queries.

Increasing caller productivity through training, motivation, and efficient tools.

• Provide comprehensive training on product knowledge and communication skills

• Implement performance incentives to motivate callers to meet and exceed targets

• Utilize efficient call center software and tools to streamline processes and improve efficiency

There are designated initializers in Swift that have specific behaviors, such as convenience init and required init.

• Designated initializers are primary initializers for a class and must call a designated initializer from its superclass.

• Convenience initializers are secondary initializers that must call another initializer in the same class.

• Required initializers must be implemented by all subclasses of a class.

SSRF is an attack that allows an attacker to send a crafted request from a vulnerable web application. CSRF is an attack that tricks a victim into performing an action on a website without their knowledge or consent.

• SSRF stands for Server-Side Request Forgery while CSRF stands for Cross-Site Request Forgery.

• SSRF allows an attacker to send a request from a vulnerable server to a third-party server while CSRF tricks a victim into performing an action on a website.

• SSRF can be us...read more

To reduce idle percentage, focus on optimizing workflow, improving communication, setting clear goals, and monitoring performance.

• Optimize workflow by identifying and eliminating bottlenecks or inefficiencies.

• Improve communication among team members to ensure tasks are being completed efficiently.

• Set clear goals and expectations for employees to keep them focused and motivated.

• Monitor performance regularly to identify areas for improvement and provide feedback.

• Implement time ...read more

I am a highly qualified and experienced professional who can provide convenience to merchants through my expertise and skills.

• Qualifications: MBA in Marketing, Certified Fintech Professional

• Experience: 10+ years in sales and marketing, 5+ years in fintech industry

• Convenience to merchant: By offering personalized solutions, optimizing processes, and providing excellent customer service

• Example: Implementing a new POS system to streamline transactions and improve efficiency

Delegate pattern is a design pattern in which an object delegates some of its responsibilities to another object.

• Create a protocol defining the methods that the delegate should implement

• Declare a delegate property in the delegating class

• Set the delegate property to the object that will act as the delegate

• Call the delegate methods from the delegating class

Rate limiter is a system that controls the rate of traffic sent or received by a network interface.

• Implement a token bucket algorithm to track and limit the rate of requests

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

• Consider using a distributed rate limiter for scalability and fault tolerance

Design a framework for exception handling in a LRU Cache system

• Implement try-catch blocks to handle exceptions

• Use specific exception classes for different types of errors

• Consider using logging mechanisms to track and debug exceptions

• Implement a global exception handler to catch unhandled exceptions

Collection is the process of recovering outstanding debts from individuals or businesses.

• Collection involves contacting debtors to remind them of their outstanding debts

• Negotiating payment plans with debtors to settle the debts

• Taking legal action if necessary to recover the debts

• Maintaining accurate records of all collection activities

• Examples: calling customers for overdue payments, sending reminder letters, negotiating settlements

Experience in developing products from ideation to launch

• Identifying market needs and opportunities

• Creating a product roadmap and strategy

• Leading cross-functional teams in product development

• Iterating on prototypes based on user feedback

• Launching and scaling the product successfully

Messaging queue system similar to Kafka for real-time data processing and streaming

• Kafka is a distributed streaming platform capable of handling high volumes of data in real-time

• It uses topics to organize data streams and partitions for scalability

• Producers publish messages to topics and consumers subscribe to topics to receive messages

• Kafka provides fault tolerance, scalability, and high throughput for data processing

• Example: Apache Kafka, Amazon Kinesis, Google Cloud Pub/Su...read more

Improve Chrome browser by optimizing performance, enhancing security, and adding new features.

• Optimize memory usage to improve performance

• Enhance security by regularly updating security protocols

• Add new features like built-in ad blocker or improved tab management

• Improve compatibility with web standards and technologies