40+ Intersoft Data Labs Interview Questions and Answers

The task is to find the minimum number of deletions needed in a string to ensure each character appears a unique number of times.

• Iterate through the string and count the frequency of each character

• Track the frequencies in a hashmap

• Identify the characters with duplicate frequencies and calculate the minimum deletions needed

• Return the minimum number of deletions for each test case

The task is to correct a Binary Search Tree by swapping two nodes in the tree.

• Parse the input level order tree and construct the BST

• Identify the two nodes that are swapped incorrectly

• Swap the values of the incorrectly swapped nodes to correct the BST

• Return the corrected BST in level order form

Answers to questions asked in an interview for Management Trainee at Amex

• 1. Amex is a reputed financial services company with a strong focus on customer service and innovation.

• 2. Closed loop model of Amex refers to the fact that Amex issues its own cards, processes transactions, and provides customer service, all within its own network.

• 3. Factors for setting credit limit include credit score, income, debt-to-income ratio, and payment history. Optimization equation: Credit Lim...read more

Find maximum sum of disjoint pairs with absolute difference less than K in an array.

• Iterate through the array and sort it.

• Find all possible disjoint pairs with absolute difference less than K.

• Calculate the sum of these pairs to get the maximum sum.

Determine if it is possible to reach the destination point from the source point using specified moves.

• Use depth-first search (DFS) to explore all possible paths from source to destination.

• Keep track of visited points to avoid infinite loops.

• Check if the destination point is reachable by following the valid moves.

• Return true if destination is reachable, false otherwise.

Count the number of islands in a 2D matrix of 1s and 0s.

• Use Depth First Search (DFS) or Breadth First Search (BFS) to traverse the matrix and identify connected groups of 1s.

• Maintain a visited array to keep track of visited cells to avoid revisiting them.

• Increment the island count each time a new island is encountered.

• Consider all eight possible directions for connectivity between cells.

• Handle edge cases like out of bounds indices and water cells (0s).

Find the length of the longest switching subarray in a given array of positive integers.

• Iterate through the array and keep track of the longest switching subarray found so far.

• Check if the numbers at even and odd positions are identical to determine a switching subarray.

• Return the length of the longest switching subarray.

• Example: For input [1, 4, 1, 4, 3, 2, 3, 0], the longest switching subarray is [1, 4, 1, 4] with length 4.

Credit card is a payment card issued to users as a method of payment.

• Credit cards allow users to borrow money up to a certain limit to make purchases.

• Users are required to pay back the borrowed amount along with interest and fees.

• Credit cards offer rewards and cashback programs to incentivize usage.

• Credit card companies charge merchants a fee for accepting payments through their network.

• Credit card fraud is a common issue and users should take precautions to protect their inf...read more

Fraud is when someone tricks or deceives others to steal their money or personal information.

• Fraud is a type of dishonest behavior where someone tries to take advantage of others for their own gain.

• It involves tricking or deceiving people to steal their money, personal information, or belongings.

• Fraud can happen in different ways, such as online scams, identity theft, or fake products.

• For example, if someone pretends to be a bank representative and asks for your credit card d...read more

Check if a singly linked list is a palindrome by comparing elements from both ends.

• Traverse the linked list to find the middle point

• Reverse the second half of the linked list

• Compare the first half with the reversed second half to check for palindrome

• Example: Input: 1 2 3 2 1 -1, Output: true

Implement a function to find maximum elements for each contiguous subarray of size K in an array of integers.

• Iterate through the array and maintain a deque to store the indices of elements in decreasing order.

• Pop elements from the deque that are out of the current window and add the maximum element to the result array.

• Return the result array containing maximum elements for each subarray of size K.

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 in the substring.

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

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

• Keep track of the longest substring length with at most K distinct characters.

• Return the length of the longest substring for each...read more

Find the intersections of two sorted lists of closed intervals.

• Iterate through both interval lists to find intersections

• Compare the intervals and find the common range

• Handle cases where there is no intersection between intervals

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 at different points.

• Keep track of the maximum profit that can be achieved by considering all possible combinations of buy and sell transactions.

• Ensure that you sell the stock before buying again to adhere to the con...read more

Count the total number of unique pairs in an array whose elements sum up to a given value.

• Use a hashmap to store the frequency of each element in the array.

• Iterate through the array and for each element, check if (Sum - current element) exists in the hashmap.

• Increment the count of pairs if the complement exists in the hashmap.

• Divide the count by 2 to avoid counting duplicates like (arr[i], arr[j]) and (arr[j], arr[i]) separately.

Implement a stack using two queues to store integer values with specified functions.

• Use two queues to simulate stack operations efficiently.

• Maintain one queue for storing elements and another for temporary storage during push operation.

• Ensure proper handling of edge cases like empty stack or invalid operations.

• Example: Push operation involves transferring elements from one queue to another before adding the new element.

• Example: Pop operation removes and returns the top elemen...read more

The minimum number of swaps required to sort a given array of distinct elements in ascending order.

• Use a graph-based approach to find cycles in the array

• Count the number of swaps needed to fix each cycle

• Sum up the swaps needed for all cycles to get the total minimum swaps

Detect and remove loop in a singly linked list in place with O(n) time complexity and O(1) space complexity.

• Use Floyd's Cycle Detection Algorithm to identify the loop in the linked list.

• Once the loop is detected, use two pointers to find the start of the loop.

• Adjust the pointers to remove the loop and return the modified linked list.

Determine if a robot's movement path is circular on a 2D grid based on a given sequence of moves.

• Iterate through the sequence of moves and keep track of the robot's position and direction.

• Check if the robot returns to the starting position after completing the moves.

• Use a counter-clockwise rotation (L) and clockwise rotation (R) to update the direction of the robot.

• Use 'G' to move the robot one unit in the current direction.

Drive 60 miles, refill, and repeat until the end of the desert.

• Drive 60 miles, which will use 60 litres of fuel

• Refill the car with 20 litres of fuel

• Repeat until the end of the desert is reached

Fraud risk refers to the potential for fraudulent activities to occur. Identifying credit card fraud involves monitoring transactions and detecting suspicious patterns.

• Fraud risk is the possibility of fraudulent activities happening, such as unauthorized use of credit cards.

• To identify credit card fraud, monitor transactions for any suspicious or unusual activity.

• Look for patterns like multiple transactions from different locations or large purchases that are inconsistent wit...read more

Print the left view of a binary tree given in level order form.

• Traverse the tree level by level and print the first node encountered at each level

• Use a queue to perform level order traversal

• Keep track of the current level and the maximum level seen so far

I utilized data management and analytics to track project progress, identify trends, and make data-driven decisions.

• Implemented data management systems to organize and store project data efficiently

• Utilized analytics tools to analyze project performance and identify areas for improvement

• Generated reports and dashboards to track key metrics and communicate findings to stakeholders

• Used data insights to make informed decisions and drive project success

I used data analysis tools to identify trends, patterns, and correlations to inform strategic business decisions.

• Utilized data visualization tools to present key findings to stakeholders

• Conducted regression analysis to predict future outcomes based on historical data

• Collaborated with cross-functional teams to gather and analyze data from multiple sources

Credit risk refers to the potential for loss due to a borrower's failure to repay a loan or meet their financial obligations.

• Credit risk is the risk that a borrower may default on their loan or fail to meet their financial obligations.

• To analyze a person's credit risk, various factors are considered such as their credit history, income level, employment stability, and debt-to-income ratio.

• Credit risk analysis involves assessing the likelihood of default and determining the ap...read more

Prevent breaking singleton pattern using reflections by throwing an exception in the private constructor.

• Throw an exception in the private constructor if an instance already exists.

• Use a flag to track if an instance has been created and throw an exception if an attempt is made to create another instance.

• Use enums to create a singleton to prevent reflection attacks.

The solution that won me the third prize in the 'Analyze this' competition was a machine learning model.

• I developed a machine learning model using Python and scikit-learn library.

• The model was trained on a large dataset of customer data and their purchasing behavior.

• It used various features such as age, gender, income, and previous purchase history to predict the likelihood of a customer making a purchase.

• I used cross-validation techniques to evaluate the model's performance ...read more

A loop in a linked list can be detected using Floyd's Cycle Detection Algorithm.

• Use two pointers - slow and fast, where slow moves one step at a time and fast moves two steps at a time.

• If there is a loop, the two pointers will eventually meet at some point within the loop.

• To detect the start of the loop, reset one pointer to the head and move both pointers one step at a time until they meet again.

The 3 pillars of data management are data quality, data governance, and data security.

• Data quality ensures that data is accurate, complete, and reliable.

• Data governance involves establishing policies and procedures for managing data assets.

• Data security focuses on protecting data from unauthorized access or breaches.

Curse of dimensionality refers to the issues that arise when working with high-dimensional data, leading to increased computational complexity and sparsity of data points.

• High-dimensional data requires exponentially more data points to maintain the same level of data density.

• Distance between data points becomes less meaningful as dimensions increase, making it harder to interpret relationships.

• Increased computational complexity and storage requirements when working with high-...read more

Regression is a statistical technique used to understand the relationship between variables and make predictions based on that relationship.

• Regression helps in identifying the strength and direction of the relationship between variables.

• It is used to predict the value of a dependent variable based on one or more independent variables.

• Common types of regression include linear regression, logistic regression, and polynomial regression.

• Example: Predicting sales based on advertis...read more

Bagging and boosting are ensemble learning techniques used to improve the performance of machine learning models by combining multiple weak learners.

• Bagging (Bootstrap Aggregating) involves training multiple models independently on different subsets of the training data and then combining their predictions through averaging or voting.

• Boosting involves training multiple models sequentially, where each subsequent model corrects the errors made by the previous ones. Examples inc...read more

Use SQL query with WHERE clause to pull data from a table based on a time interval.

• Use SQL query with SELECT statement to specify the columns you want to retrieve.

• Add a WHERE clause with the condition for the time interval, using appropriate date/time functions.

• Example: SELECT * FROM table_name WHERE timestamp_column BETWEEN 'start_time' AND 'end_time';

To maximize sales on a state level, focus on market research, targeted marketing strategies, strong customer service, and strategic partnerships.

• Conduct market research to understand the local consumer behavior and preferences

• Implement targeted marketing strategies based on the research findings

• Provide excellent customer service to build loyalty and attract repeat business

• Form strategic partnerships with local businesses or organizations to expand reach and customer base

To find the top 3 horses from a set of 25 horses, we can sort them based on their performance or rankings.

• Sort the horses based on their performance or rankings

• Select the top 3 horses from the sorted list

• Consider factors like speed, endurance, and previous race results

Design an LRU cache to store and retrieve data based on least recently used policy.

• Use a doubly linked list to keep track of the order of usage of the cache entries.

• Maintain a hash map to quickly access the cache entries based on their keys.

• When a new entry is accessed, move it to the front of the linked list to mark it as the most recently used.

• If the cache is full, remove the least recently used entry from the end of the linked list.

• Implement methods like get(key) and put(k...read more

Three ants are at the corners of an equilateral triangle. Each ant randomly picks a direction and starts moving. What is the probability that they do not collide?

• Calculate the probability of each ant moving in a direction that does not lead to a collision.

• Consider the possible outcomes for each ant and calculate the total number of favorable outcomes.

• Divide the number of favorable outcomes by the total number of possible outcomes to find the probability of no collision.

AMEX offers charge cards while Visa/Mastercard offer credit cards. AMEX has higher fees but better rewards.

• AMEX is a charge card, requiring full payment each month, while Visa/Mastercard offer credit cards with the option to carry a balance.

• AMEX typically has higher annual fees compared to Visa/Mastercard.

• AMEX is known for its premium rewards and benefits, catering to a more affluent customer base.

• Visa/Mastercard are accepted at more locations worldwide compared to AMEX.

A credit card company is a financial institution that issues credit cards to consumers for making purchases and borrowing money.

• Credit card companies issue credit cards to consumers for making purchases and borrowing money

• They charge interest on outstanding balances and fees for late payments

• They provide customer service for cardholders and handle disputes and fraud claims

• Examples include Visa, Mastercard, American Express, and Discover

OOP concepts include class, encapsulation, inheritance, and polymorphism.

• Class is a blueprint for creating objects with shared properties and methods.

• Encapsulation is the practice of hiding implementation details and exposing only necessary information.

• Inheritance allows a class to inherit properties and methods from a parent class.

• Polymorphism allows objects to take on multiple forms or behaviors depending on the context.

• Example: A class 'Car' can have properties like 'make'...read more

The number of credit cards in India can be estimated based on population, income levels, banking penetration, and consumer spending habits.

• Estimate based on population size and percentage of population with access to banking services

• Consider income levels and consumer spending habits to gauge demand for credit cards

• Look at the number of active credit card users in India and extrapolate to estimate total number of credit cards

• Take into account the growth rate of credit card us...read more

KRA's are Key Result Areas, which are specific areas of focus that define an individual's or organization's goals and objectives.

• KRA's are used to measure and evaluate performance.

• They help in setting clear expectations and priorities.

• KRA's are typically aligned with the overall goals and objectives of the organization.

• Examples of KRA's for a Complaint Analyst could be: reducing customer complaints by a certain percentage, improving complaint resolution time, increasing custo...read more

Technology is neither inherently good nor bad, but its impact depends on how it is used.

• Technology has revolutionized communication, making it easier and faster.

• It has improved efficiency and productivity in various industries.

• Technology has enabled advancements in healthcare, leading to better treatments and diagnostics.

• However, technology can also be misused, leading to privacy concerns and cybercrimes.

• It can contribute to social isolation and addiction.

• The ethical implicat...read more

Analysts gather, interpret, and present data to help organizations make informed decisions.

• Analyze data to identify trends and patterns

• Create reports and presentations to communicate findings

• Provide recommendations based on data analysis

• Use tools like Excel, SQL, and Tableau for data analysis

• Work closely with stakeholders to understand business needs

Singleton design pattern restricts the instantiation of a class to one object.

• Ensures only one instance of a class exists in the system

• Provides a global point of access to that instance

• Used when only one instance of a class is required throughout the system

• Example: Database connection manager, Logger class

American Express makes money primarily through fees charged to merchants and cardholders, as well as interest on outstanding balances.

• AMEX charges merchants a fee for accepting their cards, known as interchange fees.

• Cardholders pay annual fees, late fees, and interest on balances carried over from month to month.

• AMEX also earns revenue from its travel services, insurance products, and investment services.

• The company may also generate income from foreign exchange fees and part...read more