Oracle Application Developer Interview Questions, Process, and Tips

Round duration - 60 Minutes
Round difficulty - Medium

This was a proctured online coding test where we had 2 questions to solve under 60 minutes.

Q1. 
Minimum Cost to Connect All Points Problem Statement
Given an array COORDINATES representing the integer coordinates of some points on a 2D plane, determine the minimum cost required to connect all points...read more
Ans. 
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.
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Q2. 
Count Inversions Problem Statement
Given an integer array ARR of size N, your task is to find the total number of inversions that exist in the array.
An inversion is defined for a pair of integers in the...read more
Ans. 
Count the total number of inversions in an integer array.
• Iterate through the array and for each pair of elements, check if the conditions for inversion are met.

• Use a nested loop to compare each pair of elements efficiently.

• Keep a count of the inversions found and return the total count at the end.
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 1 question of DSA followed by some questions from DBMS and Java. I was also made to execute a SQL query at the end.

Q1. 
Remove the Kth Node from the End of a Linked List
You are given a singly Linked List with 'N' nodes containing integer data and an integer 'K'. Your task is to delete the Kth node from the end of this Lin...read more
Ans. 
Remove the Kth node from the end of a singly linked list given the position 'K'.
• Traverse the list to find the length 'N' of the linked list.

• Calculate the position from the beginning as 'N - K + 1'.

• Delete the node at the calculated position from the beginning.
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Q2. Can you explain the different types of normalization forms in a DBMS?
Ans. 
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...read more
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Q3. Can you write a SQL query that joins two tables A and B on the common attribute ID and selects records (ID_NAME) that have matching ID values in both tables?
Ans. 
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
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Q4. Why is Java considered platform independent, while the Java Virtual Machine (JVM) is platform dependent?
Ans. 
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

• Exam...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had two preety straight forward questions related to DSA and then there were 2 puzzles.

Q1. 
Find All Occurrences in Matrix
You are provided with a matrix of characters, CHARACTER_MATRIX of size M x N, and a string WORD. Your goal is to locate and display all occurrences of the string within the ...read more
Ans. 
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.

• I...read more
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Q2. 
Greatest Common Divisor Problem Statement
You are tasked with finding the greatest common divisor (GCD) of two given numbers 'X' and 'Y'. The GCD is defined as the largest integer that divides both of the...read more
Ans. 
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
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Round duration - 30 Minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions.

Q1. Why do you want to be a part of Oracle?
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The test had 15 aptitude and 2 coding questions

Q1. 1. technical questions based on OOPS
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Q2. 2. Coding question on trees
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Round duration - 60 Minutes
Round difficulty - Medium

This was an online proctured coding test where we had 2 questions to solve under 60 minutes. The questions were of Easy to Medium level.

Q1. 
Infix to Postfix Conversion
You are provided with a string EXP which represents a valid infix expression. Your task is to convert this given infix expression into a postfix expression.
Explanation:
An i...read more
Ans. 
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
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Q2. 
Subarray Challenge: Largest Equal 0s and 1s
Determine the length of the largest subarray within a given array of 0s and 1s, such that the subarray contains an equal number of 0s and 1s.
Input:
Input beg...read more
Ans. 
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.
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Round duration - 60 Minutes
Round difficulty - Medium

In this round, the interviewer asked me 2 questions related to DSA and then some questions from OS were asked to check basic understanding of the subject.

Q1. 
Palindromic Substrings Problem Statement
Given a string S, your task is to return all distinct palindromic substrings of the given string in alphabetical order.
Explanation:
A string is considered a pal...read more
Ans. 
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
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Q2. 
LCA of Binary Tree Problem Statement
You are given a binary tree consisting of distinct integers and two nodes, X and Y. Your task is to find and return the Lowest Common Ancestor (LCA) of these two nodes...read more
Ans. 
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.
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Q3. What are the differences between a mutex and a semaphore?
Ans. 
Mutex is used for exclusive access to a resource, while semaphore is used for controlling access to a resource by multiple threads.
• Mutex is binary and allows only one thread to access the resource at a time.

• Semaphore can have a count greater than one, allowing multiple threads to access the resource simultaneously.

• Mutex is used for protecting critical sections of code, while semaphore is used for synchronization betwee...read more
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Q4. Can you explain the concepts of multitasking and multiprogramming?
Ans. 
Multitasking involves executing multiple tasks simultaneously, while multiprogramming involves running multiple programs on a single processor.
• Multitasking allows multiple tasks to run concurrently, switching between them quickly.

• Multiprogramming involves loading multiple programs into memory and executing them concurrently.

• Examples of multitasking include running multiple applications on a computer or a smartphone.

• Exa...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions from DSA which were followed by some core concepts from OOPS and Java.

Q1. 
Merge Two Sorted Linked Lists Problem Statement
You are provided with two sorted linked lists. Your task is to merge them into a single sorted linked list and return the head of the combined linked list.
...read more
Ans. 
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 sorte...read more
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Q2. 
Heap Sort Problem Statement
Your task is to sort an array of integers in non-decreasing order using the Heap Sort algorithm.
Input:
The first line contains an integer 'T' denoting the number of test cas...read more
Ans. 
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).
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Q3. What is the difference between an Abstract Class and an Interface in Java?
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructors, member variables, and methods, while interface cannot have any of these.

• A class can extend only one abstract class but can implement multiple interfaces.

• Abstract classes are used to provide a common base for subclasses, while interfaces are used to define a contract for cl...read more
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Q4. Can you explain the concepts of method overloading and method overriding in object-oriented programming?
Ans. 
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.

• ...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions.

Q1. Can you tell me something about yourself?
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Q2. Why do you want to be a part of Oracle?
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Round duration - 60 Minutes
Round difficulty - Medium

This was a proctured online coding test where we had 2 questions to solve under 60 minutes. Both the questions were of Easy to Medium level of difficulty and can be solved if one has a decent command over Data Structures and Algorithms.

Q1. 
Partition Equal Subset Sum Problem
Given an array ARR consisting of 'N' positive integers, determine if it is possible to partition the array into two subsets such that the sum of the elements in both sub...read more
Ans. 
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.
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Q2. 
Count Subsequences Problem Statement
Given an integer array ARR of size N, your task is to find the total number of subsequences in which all elements are equal.
Explanation:
A subsequence of an array i...read more
Ans. 
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.
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions from DSA of Easy to Medium level in which I first had to explain my approach and then I had to code . After that, I was asked some questions from DBMS and SQL to check basic understanding of the subject.

Q1. 
Merge K Sorted Arrays Problem Statement
Given 'K' different arrays that are individually sorted in ascending order, merge all these arrays into a single array that is also sorted in ascending order.
Inpu...read more
Ans. 
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
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Q2. 
Construct Tree from Preorder Traversal
Given a list of integers pre[] of size n, representing the preorder traversal of a special binary tree where each node has 0 or 2 children, and a boolean array isLea...read more
Ans. 
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
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Q3. Explain the difference between the DELETE and TRUNCATE commands in a DBMS.
Ans. 
DELETE removes specific rows from a table, while TRUNCATE removes all rows and resets auto-increment values.
• DELETE is a DML command, while TRUNCATE is a DDL command.

• DELETE can be rolled back, while TRUNCATE cannot be rolled back.

• DELETE triggers ON DELETE triggers, while TRUNCATE does not trigger any triggers.

• DELETE is slower as it logs individual row deletions, while TRUNCATE is faster as it logs the deallocation of th...read more
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Q4. What are constraints in SQL?
Ans. 
Constraints in SQL are rules that are enforced on columns or tables to ensure data integrity and consistency.
• Constraints ensure data accuracy and reliability.

• Common constraints include NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK.

• NOT NULL constraint ensures a column cannot have a NULL value.

• UNIQUE constraint ensures that all values in a column are unique.

• PRIMARY KEY constraint uniquely identifies each record i...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round also had 2 questions from DS and Algo where I had to first explain my approach and then write the pseudo code in Google Docs. This was followed by some questions from DBMS and SQL . I was also asked to execute a SQL query at the end.

Q1. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. 
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
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Q2. 
Valid Parentheses Problem Statement
Given a string 'STR' consisting solely of the characters “{”, “}”, “(”, “)”, “[” and “]”, determine if the parentheses are balanced.
Input:
The first line contains an...read more
Ans. 
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 i
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Q3. What is the difference between a clustered index and a non-clustered index?
Ans. 
Clustered index physically reorders the data in the table, while non-clustered index does not.
• Clustered index determines the physical order of data in the table, while non-clustered index does not.

• A table can have only one clustered index, but multiple non-clustered indexes.

• Clustered index is faster for retrieval of data, as it directly points to the actual data rows.

• Non-clustered index is faster for retrieval of speci...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions.

Q1. Can you tell me something about yourself?
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Q2. Why do you want to be a part of Oracle?
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