Oracle Financial Services Software Application Developer Interview Questions and Answers

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 - 45 minutes
Round difficulty - Medium

Technical Interview round with questions on DSA.

Q1. 
Reverse Words in a String: Problem Statement
You are given a string of length N. Your task is to reverse the string word by word. The input may contain multiple spaces between words and may have leading o...read more
Ans. 
Reverse words in a string while handling leading, trailing, and multiple spaces.
• Split the input string by spaces to get individual words

• Reverse the order of the words

• Join the reversed words with a single space in between

• Handle leading, trailing, and multiple spaces appropriately
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Q2. 
Reverse a Stack Using Recursion
You are given a stack of integers. Your task is to reverse the stack using recursion without using any extra space other than the internal stack space used due to recursion...read more
Ans. 
Reverse a stack using recursion without using any extra space other than the internal stack space.
• Use recursion to pop all elements from the original stack and store them in function call stack.

• Once the stack is empty, push the elements back in reverse order.

• Base case of recursion should be when the original stack is empty.
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Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round with questions on DSA.

Q1. 
Convert a Binary Tree to its Mirror Tree
Given a binary tree, convert this binary tree into its mirror tree. A binary tree is a tree in which each parent node has at most two children. The mirror of a bin...read more
Ans. 
Convert a binary tree to its mirror tree by interchanging left and right children of all non-leaf nodes.
• Traverse the binary tree in a recursive manner.

• Swap the left and right children of each non-leaf node.

• Continue this process until all nodes have been processed.
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Q2. 
Remove Nth Node from End of Linked List
You are given a singly linked list with 'N' nodes, each containing integer data, and an integer 'K'. Your goal is to remove the 'K'th node counting from the end of ...read more
Ans. 
Remove the Kth node from the end of a singly linked list.
• Use two pointers approach to find the Kth node from the end.

• Handle edge cases like removing the head node or removing the last node.

• Update the pointers to remove the Kth node and reconnect the list.
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Round duration - 30 minutes
Round difficulty - Easy

Typical Managerial round.