Century Engineering Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Medium

Started with the discussion why do you want to join DE shaw. Since prior to my current company, I was working with a finance based company so they asked why do you want to come back to finance base company. So they asked my about debentures, bonds, mortgages and other financial jargons.
Then they asked questions related to DSA, OS etc.

Q1. 
Find Triplets with Given Sum Problem Statement
Given an array ARR consisting of N integers, your task is to identify all distinct triplets within the array that sum up to a given integer K.
Explanation:
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Ans. 
The task is to find all distinct triplets in an array that sum up to a given integer.
• Iterate through the array and use nested loops to find all possible triplets.

• Use a set to store unique triplets and avoid duplicates.

• Check if the sum of the triplet equals the target sum.

• Return the list of valid triplets or -1 if no such triplet exists.
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Q2. 
Minimum Number of Platforms Problem
Your task is to determine the minimum number of platforms required at a railway station so that no train has to wait.
Explanation:
Given two arrays:
• AT - represent...read more
Ans. 
Determine the minimum number of platforms needed at a railway station so that no train has to wait.
• Sort the arrival and departure times arrays in ascending order.

• Initialize two pointers for arrival and departure times, and a variable to keep track of the maximum number of platforms needed.

• Increment the platform count when a train arrives and decrement when a train departs.

• Update the maximum platform count as needed.

• Ret...read more
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Q3. What is the difference between internal fragmentation and external fragmentation in operating systems?
Ans. 
Internal fragmentation occurs when memory is allocated in fixed-size blocks, leading to wasted space within a block. External fragmentation occurs when free memory is fragmented into small chunks, making it difficult to allocate contiguous blocks.
• Internal fragmentation is caused by allocating fixed-size blocks of memory, leading to wasted space within a block.

• External fragmentation occurs when free memory is fragmented...read more
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Q4. Write an SQL query to find the employee with the nth highest salary.
Ans. 
SQL query to find the employee with the nth highest salary
• Use the ORDER BY clause to sort salaries in descending order

• Use the LIMIT clause to select the nth highest salary

• Join the employee table with the salary table to get the employee details
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Q5. How is Java platform independent?
Ans. 
Java is platform independent due to its bytecode and JVM.
• Java code is compiled into bytecode, which can run on any platform with a Java Virtual Machine (JVM)

• JVM acts as an intermediary between the Java code and the underlying platform, ensuring portability

• Developers write code once and it can be executed on any platform that has a compatible JVM

• Examples: Windows, macOS, Linux all can run Java programs without any chang
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Q6. 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 constructor, member variables, and methods with implementation.

• Interface can only have abstract methods and constants.

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

• Example: Abstract class - Animal with abstract method 'eat' and non-abstract method 'sle
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Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round with questions on Core Subjects mainly.

Q1. What is the difference between C and C++?
Ans. 
C is a procedural programming language while C++ is an object-oriented programming language with features like classes and inheritance.
• C is a procedural programming language, while C++ is a multi-paradigm language with support for object-oriented programming.

• C does not support classes and objects, while C++ does.

• C uses structures for data organization, while C++ uses classes for data organization.

• C does not have featur...read more
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Q2. What is a virtual function?
Ans. 
A virtual function is a function in a base class that is declared using the keyword 'virtual' and can be overridden by a function with the same signature in a derived class.
• Virtual functions allow for dynamic polymorphism in object-oriented programming.

• They are used to achieve runtime binding and enable the implementation of the function to be determined during runtime.

• Example: virtual void display() = 0; in a base cla...read more
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Q3. What is inheritance in object-oriented programming?
Ans. 
Inheritance is a concept in object-oriented programming where a class inherits properties and behaviors from another class.
• Allows for code reusability by creating a new class based on an existing class

• Child class inherits attributes and methods of the parent class

• Can have multiple levels of inheritance (e.g. grandparent, parent, child classes)

• Example: class Dog extends Animal, where Dog inherits properties and methods
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Q4. What is the difference between a Default Constructor and a Copy Constructor in Object-Oriented Programming?
Ans. 
Default Constructor is a constructor that is automatically called when an object is created without any arguments. Copy Constructor is used to create a new object as a copy of an existing object.
• Default Constructor has no parameters, while Copy Constructor takes an object of the same class as a parameter.

• Default Constructor initializes the object with default values, while Copy Constructor creates a new object with the...read more
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Round duration - 40 minutes
Round difficulty - Easy

Technical Interview round with questions on Core Subjects mainly.

Q1. What are the types of access modifiers in C++?
Ans. 
The types of access modifiers in C++ are public, private, and protected.
• Public: accessible from outside the class

• Private: only accessible within the class

• Protected: accessible within the class and its subclasses
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Q2. What is the difference between DDL (Data Definition Language) and DML (Data Manipulation Language)?
Ans. 
DDL is used to define the structure of database objects, while DML is used to manipulate data within those objects.
• DDL is used to create, modify, and delete database objects like tables, indexes, etc.

• DML is used to insert, update, delete, and retrieve data from database tables.

• DDL statements include CREATE, ALTER, DROP, TRUNCATE, etc.

• DML statements include INSERT, UPDATE, DELETE, SELECT, etc.
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Q3. What are the key differences between a Primary Key and a Unique Key in a database management system?
Ans. 
Primary Key uniquely identifies each record in a table, while Unique Key ensures that all values in a column are distinct.
• Primary Key does not allow NULL values, while Unique Key allows one NULL value.

• A table can have only one Primary Key, but multiple Unique Keys.

• Primary Key is automatically indexed, while Unique Key may or may not be indexed.

• Primary Key is used to establish relationships between tables, while Unique ...read more
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Q4. What is the difference between DBMS and RDBMS?
Ans. 
DBMS is a software system that manages databases, while RDBMS is a type of DBMS that stores data in a structured format using tables.
• DBMS stands for Database Management System, which is a software system that allows users to interact with a database.

• RDBMS stands for Relational Database Management System, which is a type of DBMS that stores data in a structured format using tables with rows and columns.

• RDBMS uses Struct...read more
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Q5. What are the objectives of normalization in database management systems?
Ans. 
Normalization in database management systems aims to reduce data redundancy, improve data integrity, and optimize database performance.
• Eliminate data redundancy by breaking down data into smaller tables

• Reduce update anomalies by ensuring data is stored in a logical and consistent manner

• Improve data integrity by enforcing referential integrity constraints

• Optimize database performance by reducing the amount of redundant
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.