Oracle Principal Software Engineer Interview Questions, Process, and Tips for Freshers

Round duration - 90 minutes
Round difficulty - Easy

Pretty easy questions.

Q1. 
Kth Smallest Element Problem Statement
You are provided with an array of integers ARR of size N and an integer K. Your task is to find and return the K-th smallest value present in the array. All elements...read more
Ans. 
Find the K-th smallest element in an array of distinct integers.
• Sort the array and return the element at index K-1.

• Use a min-heap to find the K-th smallest element efficiently.

• Implement quickselect algorithm for optimal performance.
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Round duration - 20 Minutes
Round difficulty - Easy

1 coding question

Q1. 
IP Address Formation from String
Given a string S consisting only of digits from 0 to 9, your task is to find all potential IP addresses that can be formed from S and list them in lexicographical order. I...read more
Ans. 
Given a string of digits, find all potential valid IP addresses that can be formed from it.
• Split the string into four parts and check if each part is a valid IP segment (0-255).

• Use backtracking to generate all possible combinations of valid IP addresses.

• Ensure that the IP address does not contain leading zeroes.

• Return the valid IP addresses in lexicographical order.
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Round duration - 45 Minutes
Round difficulty - Easy

Total Discussion on OS concepts

Q1. Can you explain the concepts related to memory management in operating systems?
Ans. 
Memory management in operating systems involves allocation, deallocation, and optimization of memory usage.
• Memory allocation: OS allocates memory to processes based on their requirements.

• Memory deallocation: OS frees up memory when it is no longer needed by a process.

• Memory optimization: OS optimizes memory usage through techniques like paging, segmentation, and virtual memory.

• Examples: Paging in which memory is divide...read more
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Round duration - 45 Minutes
Round difficulty - Easy

Easy in office environment

Q1. 
Find the Lone Set Bit
Your task is to identify the position of the only '1' bit in the binary representation of a given non-negative integer N. The representation contains exactly one '1' and the rest are...read more
Ans. 
Find the position of the lone '1' bit in the binary representation of a given non-negative integer.
• Iterate through the bits of the integer to find the position of the lone '1'.

• Use bitwise operations to check if there is exactly one '1' bit in the binary representation.

• Return the position of the lone '1' or -1 if there isn't exactly one '1'.
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Round duration - 120 Minutes
Round difficulty - Medium

The test included MCQ questions from SQL, Linux Commands, C/C++ programming, Logical Reasoning, Aptitude
questions. The other section was the coding round, where 2 SQL queries and 2 coding questions were there.

Q1. 
Pythagorean Triplets Detection
Determine if an array contains a Pythagorean triplet by checking whether there are three integers x, y, and z such that x² + y² = z² within the array.
Input:
The first lin...read more
Ans. 
Detect if an array contains a Pythagorean triplet by checking if there are three integers x, y, and z such that x^2 + y^2 = z^2.
• Iterate through all possible triplets of numbers in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations of three numbers from the array.

• Check if the sum of squares of any three numbers is equal to the square of another number.

• Return 'y...read more
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Q2. 
First Unique Character in a String Problem Statement
Given a string STR consisting of lowercase English letters, identify the first non-repeating character in the string and return it. If no such characte...read more
Ans. 
Identify the first non-repeating character in a string and return it, or '#' if none exists.
• Iterate through the string to count the frequency of each character

• Iterate through the string again to find the first character with frequency 1

• Return the first non-repeating character or '#' if none exists
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Round duration - 70 Minutes
Round difficulty - Medium

This was a standard DSA round where I was asked to solve 2 questions and also code it in a production ready manner . After DS and Algo , I was asked some questions from OOPS and Java followed by some Unix Commands and basic concepts from Operating Systems.

Q1. 
Find Duplicates in an Array
Given an array ARR of size 'N', where each integer is in the range from 0 to N - 1, identify all elements that appear more than once.
Return the duplicate elements in any orde...read more
Ans. 
Find duplicates in an array of integers within a specified range.
• Iterate through the array and keep track of the count of each element using a hashmap.

• Return elements with count greater than 1 as duplicates.

• Time complexity can be optimized to O(N) using a set to store duplicates.
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Q2. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
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 - prev, current, and next to reverse the linked list in O(N) time and O(1) space complexity.

• Update the head of the reversed linked list as the last node encountered during the reversal process.
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Q3. What are Serialization and Deserialization in Java?
Ans. 
Serialization is the process of converting an object into a byte stream, while deserialization is the reverse process.
• Serialization is used to persist object state or transmit objects over a network.

• Deserialization reconstructs the object from the byte stream.

• Java provides Serializable interface for serialization and ObjectInputStream/ObjectOutputStream classes for deserialization.

• Example: Serializing an object to a fi
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Q4. Can you explain the Singleton Class in Java?
Ans. 
Singleton class in Java ensures that a class has only one instance and provides a global point of access to it.
• Singleton class restricts the instantiation of a class to one object.

• It provides a way to access its unique instance globally.

• Commonly implemented using a private constructor and a static method to return the instance.

• Example: Logger class in a multi-threaded application.
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Q5. Can you explain piping in Unix/Linux?
Ans. 
Piping in Unix/Linux allows the output of one command to be used as the input for another command.
• Piping is done using the | symbol

• It helps in connecting multiple commands together to perform complex operations

• Example: ls -l | grep .txt - This command lists all files in long format and then filters out only the .txt files
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Round duration - 30 Minutes
Round difficulty - Easy

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

Q1. What is something about you that is not included in your resume?
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