20+ Opulence Wealth Labs Interview Questions and Answers

Density of a person in a social networking graph is the ratio of friends who interacted with the person to the total number of friends.

• Calculate the number of friends who interacted with the person.

• Calculate the total number of friends for that person.

• Divide the number of interacting friends by the total number of friends to get the density.

• Density = (Number of interacting friends) / (Total number of friends)

Algorithm to find median in a stream of n numbers

• Sort the list and find the middle element for odd n

• For even n, find the average of middle two elements

• Use a min-heap and max-heap to maintain the smaller and larger half of the stream respectively

• Insert new elements into the appropriate heap and balance the heaps to ensure median is always at the top

Given 2 arrays with n and n-1 elements, find the unique element in the larger array.

• Loop through the larger array and check if each element is present in the smaller array.

• If an element is not present in the smaller array, it is the unique element.

• Return the unique element.

• Example: arr1 = ['a', 'b', 'c', 'd'], arr2 = ['a', 'b', 'c'], unique element = 'd'

Given a map of coffee shops and a person, find the closest n coffee shops to him.

• Use the person's location and calculate the distance to each coffee shop on the map.

• Sort the coffee shops by distance and return the closest n.

• Consider using a data structure like a priority queue to efficiently find the closest coffee shops.

Given 2 arrays, one with n elements and another with n-1 elements, answer the question.

• Compare the elements of both arrays to find the missing element.

• Use a loop or a built-in function to iterate through the arrays.

• Consider edge cases where the missing element is at the beginning or end of the array.

Xpath and CSS are used to locate web elements on a webpage.

• Xpath is a language used to navigate through the XML structure of a webpage.

• CSS selectors are used to target specific HTML elements on a webpage.

• Xpath can be used to locate elements based on their attributes, text content, or position on the page.

• CSS selectors can be used to locate elements based on their tag name, class, ID, or attributes.

• Both Xpath and CSS can be used in automated testing frameworks like Selenium to...read more

Dynamic programming is a technique to solve complex problems by breaking them down into smaller subproblems.

• It involves solving subproblems only once and storing their solutions for future use.

• It is used in optimization problems, such as finding the shortest path or maximizing profit.

• Examples include the knapsack problem and the Fibonacci sequence.

• It can be implemented using either a top-down or bottom-up approach.

• Dynamic programming requires both optimal substructure and ove...read more

Garbage collection is an automatic memory management process.

• It frees up memory that is no longer being used by the program.

• It helps prevent memory leaks and crashes caused by running out of memory.

• Examples include Java's garbage collector and Python's reference counting.

• Garbage collection can have an impact on performance and should be tuned accordingly.

Ext file system is a widely used file system in Linux for organizing and managing files on storage devices.

• Ext stands for Extended File System

• Supports features like journaling, access control lists, and extended attributes

• Uses inodes to store metadata about files and directories

• Supports different block sizes for efficient storage allocation