Optimum Infosystem Senior Java Developer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Medium

21 students were shortlisted from the 1st MCQ round and in this round we were asked to write the codes (function only) of 3 questions in 1 hour time.

Q1. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
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Q2. 
Majority Element Problem Statement
Given an array/list 'ARR' consisting of 'N' integers, your task is to find the majority element in the array. If there is no majority element present, return -1.
Exampl...read more
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Q3. 
Maximum Path Sum Between Two Leaves Problem Description
You are provided with a non-empty binary tree in which each node contains a non-negative integer value. Your task is to find and return the maximum ...read more
Ans. 
Find the maximum path sum between two leaf nodes in a binary tree.
• Traverse the tree to find the maximum path sum between two leaf nodes.

• Keep track of the maximum sum found so far.

• Consider all possible paths between leaf nodes.

• Handle cases where the tree has only a single leaf node.

• Implement a recursive function to calculate the maximum path sum.
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Round duration - 60 minutes
Round difficulty - Medium

This was a technical round with DSA based questions.

Q1. 
N-th Node From The End Problem Statement
You are given a Singly Linked List of integers. The task is to find the N-th node from the end of the list.
Example:
Input:
If the given list is (1 -> -2 -&g...read more
Ans. 
Find the N-th node from the end of a Singly Linked List of integers.
• Traverse the list to find the length L of the list.

• Calculate the position of the N-th node from the beginning as L - N + 1.

• Traverse the list again to reach the calculated position and return the node's value.
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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
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Q3. 
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
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Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions based on DSA

Q1. 
Minimum Time To Solve The Problems
Given 'N' subjects, each containing a certain number of problems, and 'K' friends, assign subjects to friends such that each subject goes to exactly one friend, maintain...read more
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Q2. What is grammar in the context of compiler design?
Ans. 
Grammar in compiler design defines the syntax and structure of a programming language.
• Grammar specifies the rules for forming valid statements in a programming language.

• It consists of a set of production rules that define how valid programs can be constructed.

• There are different types of grammars such as context-free grammar, regular grammar, etc.

• Example: In C programming language, the grammar specifies that a for loop...read more
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Q3. What is a token in compiler design?
Ans. 
A token in compiler design is a basic unit of syntax that the compiler can understand and process.
• Tokens are the smallest units of a program that are meaningful to the compiler.

• Examples of tokens include keywords, identifiers, operators, and punctuation symbols.

• Tokens are generated by the lexical analysis phase of the compiler.

• Tokens are used by the parser to build the abstract syntax tree of the program.
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Round duration - 60 minutes
Round difficulty - Easy

Technical round with questions on DSA and Compiler Design mainly. He told me that you’ll be having your final HR round in some time. I knew that I was going well because he seemed to be quite satisfied with my answers.

Q1. 
Sum Root to Leaf Numbers
You are given an arbitrary binary tree consisting of N nodes, each associated with an integer value from 1 to 9. Each root-to-leaf path can be considered a number formed by concat...read more
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Q2. What is a regular language?
Ans. 
A regular language is a language that can be recognized by a finite automaton.
• Regular languages can be described by regular expressions.

• Regular languages are closed under union, concatenation, and Kleene star operations.

• Examples of regular languages include the set of all strings over an alphabet that contain an even number of 'a's.
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Q3. What are NP and NP-Hard problems?
Ans. 
NP problems are decision problems that can be verified in polynomial time, while NP-Hard problems are at least as hard as the hardest problems in NP.
• NP problems can be verified in polynomial time but not necessarily solved in polynomial time.

• NP-Hard problems are at least as hard as the hardest problems in NP, but may not be in NP themselves.

• Examples of NP problems include the subset sum problem and the traveling salesm...read more
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Round duration - 30 minutes
Round difficulty - Easy

That was the round for which I’ve been waiting for hours 
She was very friendly and nice to talk to. It didn’t seem that I was talking to the HR. It was more like talking to a friend. Finally we discussed about the pay-scale and work culture in Accolite.