Wi4 Interview Questions and Answers

90 minute test on hacker rank consisting of 3 coding questions all of medium difficulty. Most candidates are required to solve more than 1 question.

Q1. Questions on concepts of OOPS and Operating Systems.
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Q2. Find least common ancestor of a binary tree.
Ans. 
Find the lowest common ancestor of a binary tree.
• Traverse the tree recursively from the root node.

• If the current node is null or matches either of the given nodes, return the current node.

• Recursively search for the nodes in the left and right subtrees.

• If both nodes are found in different subtrees, return the current node.

• If both nodes are found in the same subtree, continue the search in that subtree.
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Q3. Find first missing positive integer from an array for non-negative integers.
Ans. 
Find first missing positive integer from an array of non-negative integers.
• Create a hash set to store all positive integers in the array

• Loop through the array and add all positive integers to the hash set

• Loop through positive integers starting from 1 and return the first missing integer not in the hash set
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Q1. Design a parking lot
Ans. 
Design a parking lot
• Consider the size and capacity of the parking lot

• Decide on the layout and organization of parking spaces

• Implement a system to manage parking availability and reservations

• Include features like ticketing, payment, and security

• Consider scalability and future expansion
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Q1. Given a grid which represents an ocean( For all index i,j if mat[i][j] = 1 is island and mat[i][j] = 0 means water). Find the island with largest area.
Ans. 
Find the largest island area in a grid representing an ocean using DFS or BFS.
• Use Depth-First Search (DFS) or Breadth-First Search (BFS) to explore the grid.

• Mark visited cells to avoid counting them multiple times.

• Count the size of each island during the traversal.

• Example: For a grid [[1,0,0],[1,1,0],[0,0,1]], the largest island has area 3.

• Keep track of the maximum area found during the exploration.
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Q2. Given list of strings group them into distinct anagrams.
Ans. 
Group list of strings into distinct anagrams.
• Create a hash table with sorted string as key and list of anagrams as value.

• Iterate through the list of strings and add each string to its corresponding anagram list in the hash table.

• Return the values of the hash table as a list of lists.
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Q1. Who is a BA Role of a BA Scenario based questions Questions in area of interest Questions on project
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Basic aptitude questions but less time to solve.

Basic topics given such as social media and work life balance.

Q1. Self introduction
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Q2. Why did you choose our company?
Ans. 
I chose your company because of its reputation for innovation and commitment to employee development.
• Impressed by the company's track record of successful projects

• Positive reviews from current and former employees

• Opportunities for growth and advancement within the company
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Logical thinking and quantitative

One Java and one SQL and one js question

Q1. What is collections
Ans. 
Collections are data structures that store and organize multiple elements in a single unit.
• Collections provide methods to add, remove, and manipulate elements.

• Examples of collections include arrays, lists, sets, and maps.

• Collections can be used to efficiently manage and access large amounts of data.
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Q2. What is constructor
Ans. 
A constructor is a special method in a class that is automatically called when an object of that class is created.
• Constructors have the same name as the class they belong to

• They are used to initialize the object's state

• Constructors can have parameters to customize the initialization process
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Q3. What is data science
Ans. 
Data science is a field that uses scientific methods, algorithms, and systems to extract knowledge and insights from structured and unstructured data.
• Data science involves collecting, analyzing, and interpreting large amounts of data to make informed decisions.

• It combines statistics, machine learning, and domain knowledge to uncover patterns and trends in data.

• Data scientists use programming languages like Python and R...read more
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Q1. Requirement gathering kind of questions
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Q2. Past experience working based questions
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Q1. Pivot table in excel
Ans. 
Pivot table is a data summarization tool in Excel.
• Pivot table allows users to summarize and analyze large datasets.

• It can be used to group data by categories, calculate totals, and create custom calculations.

• Users can easily change the layout of the table to view data in different ways.

• Pivot table is a powerful tool for data analysis and reporting.

• Example: A sales manager can use pivot table to analyze sales data by re...read more
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Q2. How to count data in excel
Ans. 
To count data in Excel, use the COUNT function or select the data and look at the status bar.
• Use the COUNT function to count the number of cells that contain numbers or dates

• Use the COUNTA function to count the number of cells that are not empty

• Select the data and look at the status bar to see the count of selected cells

• Use the COUNTIF function to count cells that meet a specific criteria
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