Dell EMC Java Developer Interview Questions and Answers

Print all possible paths from start to end in a linear way, moving either one or two steps right.

• Use dynamic programming to solve the problem

• Create a 2D array to store the number of paths to each position

• Start from the end position and work backwards

• At each position, calculate the number of paths by summing the number of paths from the next two positions

• Print all the paths by backtracking from the start position

The program prints the substring after a specified character has occurred a certain number of times in a given string.

• Iterate through the string to find the specified character.

• Keep track of the count of occurrences of the character.

• Once the count reaches the specified count, extract the substring after that position.

• Handle corner cases such as when the character is not in the string or when it doesn't occur the specif

Design a website similar to bookmyshow.com for booking cinema tickets for a single location with multiple theatres.

• Design a user-friendly GUI with options for advance booking, user login, user registration, movie rating, and saving card details.

• Create relevant database tables to store information about movies, theatres, bookings, user details, and card details.

• Link the GUI to the database to enable data flow and retrie...read more

The algorithm for the upcoming semester project involves developing an application.

• Identify the requirements and objectives of the project

• Design the application architecture and user interface

• Implement the necessary algorithms and data structures

• Test and debug the application

• Optimize the performance and efficiency of the code

• Document the project for future reference

My favorite subject is computer science.

• I enjoy learning about algorithms and data structures.

• I find programming languages fascinating and love exploring their features.

• I am passionate about software development and enjoy creating applications.

• I find the process of problem-solving in application development fulfilling.

• I appreciate the continuous learning opportunities in this field.

Implementing queue using linked lists

• Create a Node class with data and next pointer

• Create a Queue class with head and tail pointers

• Enqueue by adding a new node at the tail and dequeue by removing the head node

• Check for empty queue by checking if head is null

Reverse a string

• Use a loop to iterate through the string and append each character to a new string in reverse order

• Alternatively, use the built-in reverse() method for strings in some programming languages

Count the number of palindromes in a given string.

• A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward.

• Iterate through the string and check if each substring is a palindrome.

• Use two pointers, one at the beginning and one at the end of the substring, and move them towards each other until they meet in the middle.

• If the substring is a palindrome, increment the c...read more

Interfaces in Java define a contract for classes to implement certain methods.

• Interfaces are like a blueprint for classes to follow

• They can contain method signatures but no implementation

• Classes can implement multiple interfaces

• Interfaces can extend other interfaces

• Example: Comparable interface for sorting objects

Overloading is when multiple methods have the same name but different parameters. Overriding is when a subclass provides a different implementation of a method inherited from its superclass.

• Overloading allows a class to have multiple methods with the same name but different parameters.

• Overriding occurs when a subclass provides a different implementation of a method inherited from its superclass.

• Overloading is resolved ...read more

Abstract classes in Java are classes that cannot be instantiated and are used as blueprints for other classes.

• Abstract classes cannot be instantiated, meaning you cannot create objects of an abstract class.

• Abstract classes can have both abstract and non-abstract methods.

• Interfaces in Java are similar to abstract classes, but they cannot have any method implementations.

• A class can implement multiple interfaces, but it c...read more

Find the fifth largest element in a linked list

• Traverse the linked list and store the elements in an array

• Sort the array in descending order

• Return the fifth element in the sorted array

Find the common ancestor of two given nodes in a tree

• Traverse the tree from the root node

• Check if both nodes are on the same side of the current node

• If not, return the current node as the common ancestor

• If yes, continue traversing down that side of the tree

Heap sort is a comparison-based sorting algorithm that uses a binary heap data structure.

• It divides the input into a sorted and an unsorted region.

• It repeatedly extracts the largest element from the unsorted region and inserts it into the sorted region.

• It has a worst-case and average-case time complexity of O(n log n).

Find duplicates in an array

• Iterate through the array and compare each element with the rest of the elements

• Use a hash table to keep track of the frequency of each element

• Sort the array and compare adjacent elements

• Use a set to keep track of unique elements and add duplicates to another set

Merge two sorted linked lists

• Create a new linked list to store the merged list

• Compare the first nodes of both lists and add the smaller one to the new list

• Move the pointer of the added node to the next node

• Repeat until one of the lists is empty, then add the remaining nodes to the new list

Explanation of three normalizations with examples

• First Normal Form (1NF): Eliminate duplicate data and create separate tables for related data

• Example: A table with customer information and their orders should be split into two tables

• Second Normal Form (2NF): Ensure non-key attributes are dependent on the primary key

• Example: A table with customer information and their orders should have separate tables for customer and ...read more

To find the maximum salary in emp table, use the MAX function on the salary column.

• Use the MAX function in SQL to find the highest value in a column

• Specify the column name after the MAX function, in this case 'salary'

• Example: SELECT MAX(salary) FROM emp

• This will return the highest salary value in the emp table

Query to find the employee with highest salary and their department.

• Use MAX() function to find the highest salary.

• Join the employee and department tables using the department ID.

• Select the name and department of the employee with the highest salary.

Semaphore allows multiple threads to access shared resources at the same time, while mutex allows only one thread at a time.

• Semaphore is used to control access to a resource with limited capacity, like a printer or database connection pool.

• Mutex is used to protect a shared resource from simultaneous access, like a critical section of code.

• Semaphore can have a count greater than 1, allowing multiple threads to access th...read more

The minimum number of races required to find the top 3 among 25 horses is 7.

• Divide the 25 horses into 5 groups of 5 horses each.

• Race the 5 groups, which will give us the top 3 horses from each group.

• Now we have 15 horses remaining.

• Race the top 3 horses from each group, which will give us the top 3 horses overall.

• This requires a total of 7 races.

Undo operation (ctrl + z) is implemented by maintaining a stack of previous states.

• When a change is made, the current state is pushed onto the stack

• When undo is called, the top state is popped and applied

• Redo is implemented by maintaining a stack of undone states

• Some applications may also implement a limit on the number of undo/redo steps

• Undo/redo can be implemented at different levels (e.g. character, word, paragraph)

8 Queens Algorithm is a backtracking algorithm to place 8 queens on a chessboard without attacking each other.

• The algorithm places one queen in each column, starting from the leftmost column.

• If a queen can be placed in a row without attacking another queen, it is placed there.

• If no such row exists, the algorithm backtracks to the previous column and tries a different row.

• The algorithm continues until all 8 queens are p...read more

The time complexity of 8 queens algorithm is O(n!).

• The algorithm checks all possible permutations of the queens on the board.

• The number of permutations is n! where n is the number of queens.

• For 8 queens, there are 8! = 40,320 possible permutations.

• The algorithm has to check each permutation to find a valid solution.

• Therefore, the time complexity is O(n!).

Towers of Hanoi is a classic problem of moving disks from one peg to another with specific rules.

• The problem involves three pegs and a number of disks of different sizes.

• The goal is to move all the disks from the first peg to the third peg, while following the rules.

• The rules are: only one disk can be moved at a time, a larger disk cannot be placed on top of a smaller disk, and all disks must be moved to the third peg.

• ...read more

ER diagrams are used to visualize and design relational databases.

• ER diagrams show the relationships between entities in a database

• They help in identifying the attributes of each entity

• They aid in designing the structure of a database

• ER diagrams are commonly used in software development

My favorite program is Visual Studio Code because of its user-friendly interface and extensive plugin library.

• User-friendly interface with customizable settings

• Extensive plugin library for various programming languages and tools

• Integrated terminal and debugging features

• Supports Git version control

• Frequent updates and improvements

• Free and open-source

• Examples: Python, JavaScript, HTML/CSS, Git

Count the frequency of each alphabet in a string.

• Iterate through the string and count the occurrence of each alphabet using a dictionary or array.

• Convert the string to lowercase or uppercase to avoid case sensitivity.

• Exclude non-alphabetic characters using regular expressions.

• Consider using built-in functions or libraries for efficiency.

• Handle edge cases such as empty strings or strings with no alphabetic characters.