500+ Application Developer Interview Questions and Answers

The problem involves finding the minimum cost to connect all points on a 2D plane using Manhattan distance.

• Create a function that calculates the Manhattan distance between two points.

• Implement a function to find the minimum spanning tree to connect all points.

• Consider using Prim's or Kruskal's algorithm for finding the minimum spanning tree.

• Ensure that all points are connected with one simple path only.

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.

The game is not fair.

• Player X has a higher chance of winning as they only need to get a consecutive HEAD, TAIL.

• Player Y needs to get a consecutive HEAD, HEAD which is less likely to occur.

• The probability of Player X winning is higher than Player Y winning.

Count the total number of subsequences in which all elements are equal in an integer array.

• Iterate through the array and count the frequency of each element.

• Calculate the total number of subsequences for each element using the formula (frequency * (frequency + 1)) / 2.

• Sum up the total number of subsequences for all elements and return the result modulo 10^9 + 7.

The last ball that will be left is black.

• When you take out 2 black balls, you take another white ball.

• If you take 2 white balls, you take out 1 black ball.

• If balls are of different color, you take out another black ball.

• Since there are more black balls initially, the last ball will be black.

tmap is used to transform data in Talend, tjoin is used to join data. There are different types of connections, truncate and delete are different ways to remove data from a table. ETL stands for Extract, Transform, Load. Triggers are database objects that are automatically executed in response to certain events. There are different types of joins.

• tmap is used for data transformation in Talend

• tjoin is used for joining data in Talend

• Types of connections include database connect...read more

Return all distinct palindromic substrings of a given string in alphabetical order.

• Iterate through all possible substrings of the given string

• Check if each substring is a palindrome

• Store distinct palindromic substrings in alphabetical order

The goal is to find all occurrences of a given string in a matrix in all eight possible directions.

• Iterate through each cell in the matrix and check for the starting character of the word.

• For each starting character found, check in all eight directions for the complete word.

• Keep track of the coordinates of each character in the word for each occurrence.

• Print the coordinates of each character for each occurrence found.

• If no occurrences are found, output 'No match found'.

Find the Lowest Common Ancestor (LCA) of two nodes in a binary tree.

• Traverse the binary tree to find the paths from the root to nodes X and Y.

• Compare the paths to find the last common node, which is the LCA.

• Handle cases where one node is an ancestor of the other.

• Consider edge cases like when X or Y is the root node.

• Implement a recursive or iterative solution to find the LCA efficiently.

The task is to determine if it is possible to partition an array into two subsets with equal sum.

• Iterate through all possible subsets of the array using recursion.

• Keep track of the sum of elements in each subset.

• Check if the sum of elements in both subsets is equal.

The task is to determine if a given string consisting of parentheses is balanced or not.

• Iterate through each character in the string and use a stack to keep track of opening parentheses

• If an opening parenthesis is encountered, push it onto the stack

• If a closing parenthesis is encountered, check if it matches the top of the stack. If not, the string is not balanced

• If all parentheses are matched correctly and the stack is empty at the end, the string is balanced

Construct a binary tree from preorder traversal and leaf node information.

• Create a binary tree using preorder traversal and leaf node information

• Use recursion to build the tree

• Identify leaf nodes based on the isLeaf array

• Handle multiple test cases separately

Heap Sort algorithm is used to sort an array of integers in non-decreasing order.

• Implement Heap Sort algorithm to sort the array in non-decreasing order.

• Use a max heap to sort the array in ascending order.

• Time complexity of Heap Sort is O(n log n).

Merge K sorted arrays into a single sorted array.

• Create a min heap to store the first element of each array along with the array index.

• Pop the root of the heap (smallest element) and add it to the result array.

• If the array from which the element was taken has more elements, add the next element to the heap.

• Repeat until all elements are processed.

• Time complexity: O(N log K) where N is the total number of elements and K is the number of arrays.

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 retrieval.

• Implement features like advance booking, where users c...read more

A database for managing songs on Spotify playlists.

• Create a table for playlists with columns for name, description, and user ID

• Create a table for songs with columns for title, artist, album, and duration

• Create a table for playlist-songs with columns for playlist ID and song ID

• Use foreign keys to link tables together

• Allow for CRUD operations on playlists and songs

Determine if two strings are anagrams of each other by checking if they have the same characters in different order.

• Create character frequency maps for both strings and compare them.

• Sort both strings and compare them.

• Use a hash table to store character counts and check if they are equal for both strings.

Transpose a given matrix by switching rows and columns.

• Iterate through the matrix and swap elements at [i][j] with [j][i].

• Create a new matrix to store the transposed values.

• Ensure the dimensions of the transposed matrix are switched from the original matrix.

Update Dashboard/Homepage when there is a DB update

• Use a backend service to monitor the DB for updates

• When an update is detected, fetch the updated data from the DB

• Update the Dashboard/Homepage with the new data using a frontend framework like React or Angular

Convert a given infix expression to a postfix expression.

• Use a stack to keep track of operators and operands

• Follow the rules of precedence for operators

• Convert the infix expression to postfix using the stack

• Handle parentheses by pushing them onto the stack and popping when necessary

Merge two sorted linked lists into a single sorted linked list with linear time complexity and constant space usage.

• Iterate through both linked lists simultaneously, comparing elements and merging them into a new linked list

• Update the pointers of the new linked list as you merge elements from the two input linked lists

• Ensure to handle cases where one linked list is empty or both linked lists are empty

• Maintain the sorted order while merging the elements from the two linked lis...read more

Given a sorted N * N matrix, find the position of a target integer X.

• Iterate through each row and column to search for the target integer

• Utilize the sorted nature of the matrix to optimize the search process

• Return the position of the target integer if found, else return -1 -1

Find the length of the largest subarray with equal number of 0s and 1s in a given array.

• Iterate through the array and maintain a count of 0s and 1s encountered so far.

• Store the count difference in a hashmap with the index as the key.

• If the same count difference is encountered again, the subarray between the two indices has equal 0s and 1s.

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 specified number of times.

To efficiently manage room bookings and prebookings in a hotel, a priority queue data structure can be implemented.

• A priority queue can be used to prioritize room bookings based on check-in dates.

• When a customer checks out, the room becomes available and can be assigned to the next customer in the priority queue.

• Prebookings can be stored separately and checked against the availability of rooms before assigning them to customers.

• The priority queue can be implemented using a bi...read more

Finding the greatest common divisor (GCD) of two given numbers 'X' and 'Y'.

• Iterate through each test case

• Use Euclidean algorithm to find GCD

• Output the GCD for each test case

Ansible playbooks automate configuration management. CI/CD pipeline automates software delivery. Tools include Jenkins, GitLab, and Travis CI.

• Ansible playbooks are written in YAML format and define tasks to be executed on remote hosts.

• CI/CD pipeline automates the software delivery process from code commit to production deployment.

• Tools for pipeline creation include Jenkins, GitLab, Travis CI, and CircleCI.

• Pipeline creation involves defining stages, jobs, and triggers to autom...read more

Yes, I can write a SQL query to join two tables on a common attribute and select matching records.

• Use INNER JOIN to join tables A and B on the common attribute ID

• Select the records (ID_NAME) where ID values match in both tables

Java is platform independent because the code is compiled into bytecode that can run on any system with a JVM, which is platform dependent.

• Java code is compiled into bytecode, which is a platform-independent intermediate code

• The JVM interprets and executes the bytecode on different platforms, making it platform dependent

• The JVM acts as a layer of abstraction between the Java code and the underlying operating system

• Example: A Java program compiled on a Windows machine can run ...read more

Minimum number of times to turn all glasses upside down when 4 can be turned at a time.

• Turn over any four glasses, leaving one untouched.

• Repeat the above step until only one glass is left upside down.

• Finally, turn over the last glass to complete the task.

• Minimum number of turns required is 3.

JVM allocates 5 types of memory areas: Heap, Stack, Method Area, PC Register, and Native Method Stack.

• Heap is used for storing objects and is shared among all threads.

• Stack is used for storing method calls and local variables, each thread has its own stack.

• Method Area stores class structures, method data, and static variables.

• PC Register stores the address of the currently executing instruction.

• Native Method Stack is used for native method calls.

Minimum 7 races required to find the top 3 fastest horses.

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

• Conduct a race among the horses in each group to determine the fastest horse in each group.

• Take the top 2 horses from each group and conduct a race among them to determine the fastest horse overall.

• The winner of this race is the fastest horse.

• Now, take the second-place horse from the final race and the second-place horse from each group race.

• Conduct a race among these...read more

Normalization forms in a DBMS help reduce data redundancy and improve data integrity.

• 1NF (First Normal Form) - Each column contains atomic values, and there are no repeating groups.

• 2NF (Second Normal Form) - Meets 1NF and all non-key attributes are fully functional dependent on the primary key.

• 3NF (Third Normal Form) - Meets 2NF and there are no transitive dependencies between non-key attributes.

• BCNF (Boyce-Codd Normal Form) - Every determinant is a candidate key.

• 4NF (Fourth ...read more

The @RestController annotation is a specialized version of the @Controller annotation in Spring MVC.

• The @Controller annotation is used to define a controller class in Spring MVC.

• The @RestController annotation is used to define a RESTful web service controller.

• The @RestController annotation is a combination of @Controller and @ResponseBody annotations.

• The @Controller annotation returns a view while the @RestController annotation returns data in JSON or XML format.

• Example: @Con...read more

Create an array of song titles sorted by year of publication.

• Create an array of song objects with properties for title and year of publication.

• Sort the array by year of publication.

• Extract the titles of the songs into a separate array.

• Return the array of song titles.

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 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.

It depends on the use case. QuickSort is generally the fastest, but MergeSort is more stable and efficient for larger datasets.

• QuickSort is generally the fastest sorting algorithm, but can be unstable for certain datasets.

• MergeSort is more stable and efficient for larger datasets, but can be slower than QuickSort for smaller datasets.

• InsertionSort is efficient for small datasets, but can be slow for larger datasets.

• HeapSort is efficient for larger datasets, but can be slower ...read more

Method overloading is when multiple methods in the same class have the same name but different parameters. Method overriding is when a subclass provides a specific implementation of a method that is already provided by its superclass.

• Method overloading allows a class to have multiple methods with the same name but different parameters. For example, having multiple constructors in a class with different parameter lists.

• Method overriding occurs when a subclass provides a specif...read more

The words in a string can be arranged based on their order of occurrence.

• Split the string into an array of words

• Create a dictionary to store the count of each word

• Sort the array based on the count of each word

• Join the sorted array back into a string

Spring Boot offers basic annotations like @SpringBootApplication, @RestController, @Autowired, @RequestMapping, @ComponentScan.

• @SpringBootApplication - Used to mark the main class of a Spring Boot application.

• @RestController - Used to define RESTful web services.

• @Autowired - Used for automatic dependency injection.

• @RequestMapping - Used to map web requests to specific handler methods.

• @ComponentScan - Used to specify the base packages to scan for Spring components.

Interview questions for application developer including Python applications, PEP8, CSS, input handling, list vs tuples, and willingness to relocate.

• Python is used for web development, data analysis, machine learning, and more

• PEP8 is a style guide for Python code

• CSS stands for Cascading Style Sheets and is used for styling web pages

• To find input3, use input3 = input1 + input2

• To resolve issues with colleagues, communicate and collaborate effectively

• Lists and tuples are both use...read more

ArrayList is non-synchronized and Vector is synchronized in Java.

• ArrayList is not synchronized, while Vector is synchronized.

• ArrayList is faster than Vector as it is not synchronized.

• Vector is thread-safe, while ArrayList is not.

• Example: ArrayList<String> list = new ArrayList<>(); Vector<String> vector = new Vector<>();

Probability of a stone thrown in a circle with radius r lying near the center.

• The probability of the stone lying near the center is directly proportional to the area of the circle near the center.

• The area of the circle near the center is proportional to the square of the radius.

• Therefore, the probability of the stone lying near the center is proportional to the square of the radius.

• The probability can be calculated by dividing the area of the circle near the center by the tot...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 can only extend one abstract class.

• Abstract classes can hav...read more

The starter dependency of the Spring Boot module is spring-boot-starter-parent.

• The starter dependency provides a set of default configurations and dependencies for Spring Boot applications.

• It helps in reducing the amount of boilerplate code needed to set up a Spring Boot project.

• The spring-boot-starter-parent is typically used as the parent project in a Spring Boot application's pom.xml file.

Different types of waits in Selenium WebDriver include Implicit Wait, Explicit Wait, and Fluent Wait.

• Implicit Wait: Waits for a certain amount of time before throwing a NoSuchElementException.

• Explicit Wait: Waits for a certain condition to occur before proceeding further in the code.

• Fluent Wait: Waits for a condition to be true with a specified polling frequency and timeout.