Explore topic-wise InterviewSolutions in .

Example:
Input:
str = “InterviewBit is best”
Output :
best is InterviewBit

We maintain a vector of strings. We traverse the given string and keep forming the word until a space is encountered. When space is encountered we ADD the word formed to the vector of strings. In the end, we print the vector of strings in reverse format.

Code :

Output :

Explanation :

In the above code, the function displayModifiedString takes a string input and displays the modified string with words in reverse order. We keep forming a word until a space character is found. Once space is found, we push back the word to the vector. Lastly, we display the vector in reverse order.

Example:
Input :
arr1 = {2, 3, 0, 5, 1, 1, 2}
ARR2 = {3, 0, 5, 1}
Output :
True

Input :
arr1 = {3, 4, 5, 1, 2, 7}
arr2 = {4, 1, 2}
Output :
False

We use two pointers to explore both the ARRAY and the subarray. We maintain the pointer of array arr2[] and increase the pointer of both ARRAYS if any element of arr1[] matches the first element of arr2[], otherwise set the pointer of arr1 to the next element of the previous starting point and reset the pointer of arr2 to 0. If all of arr2's elements match, print True; otherwise, print False.

The following is how the above strategy is put into action:

Code:

EXPLANATION:

In the above code, the function checkSubArray checks whether the second array is a sub array of the first array or not and returns the output correspondingly. We maintain two pointers, one for the first array and the other for the second array. If the elements match, we increment both the pointers; otherwise, we reset the pointers.

Following are the differences between SQL and NoSQL databases:

 Following are the differences between preemptive and non-preemptive scheduling algorithms:

Following are the advantages of subnetting :

• It PROTECTS one network from the INTRUSION of another. For example, in an organisation, the Developer department's code must not be accessible by any other department.
• It's possible that some subnets will require higher network priority than others. A sales department, for example, may need to host webcasts or VIDEO conferences. Subnetting makes it possible to treat networks with different priorities differently.
• Maintenance is simple in the case of small networks.

Following are the disadvantages of subnetting :

• To reach a Process in the case of a single network, only three steps are required: Source Host to Destination Network, Destination Network to Destination Host, and lastly Destination Host to Process. Subnetting, on the other hand, necessitates four phases for Inter-Network Communication. Source Host to Destination Network, Destination Network to appropriate Subnet, Subnet to Host, and lastly Host to Process are the steps. As a result, Time complexity rises. More time is necessary for communication or data transfer in the case of Subnet.
• Only two IP addresses are spent for Network Id and Broadcast ADDRESS in a single network, while two IP addresses are wasted for each Subnet in subnetting.
• The total Network's COST rises as well. Subnetting necessitates the purchase of expensive internal routers, switches, hubs, and bridges.

Subnetting is the PROCESS of dividing a larger network into smaller networks in order to preserve security. As a result, smaller networks are easier to maintain. To divide a network into two pieces, select ONE bit from the host ID part for each Subnet. To divide a network into four subnets, two bits from the host id component must be CHOSEN for each subnet and so on.

In the above image, we can SEE that we have divided the network 20.0.0.0/24 into two subnets 20.0.1.0/24 and 20.0.3.0/24.

name - denoting the name of the employee
SALARY - denoting the salary of the employee 

We USE the dense_rank() function to display the details of the employee having the nth highest salary. The function DENSE_RANK returns the rank of a row in an ordered collection of rows as a NUMBER. The ranks are in ascending order, starting with 1. Based on the values of the value exprs in the order by clause, DENSE RANK computes the rank of each row returned from a query in relation to the other rows as an analytic function.

Query:

Explanation:

In the above query, we first sort the data according to the descending order of the salary and assign a rank to each of the EMPLOYEES starting from 1. In case of an EVENT where the salary of two employees is the same, they both are assigned the same rank. Then we display the data whose rank is equal to the given input.

The following table lists the differences between the WHERE CLAUSE and the HAVING clause:

Following are the different layers in the OSI model:

Physical Layer: The physical layer is the lowest layer in the OSI reference model. It is in charge of establishing a physical connection between the devices. BITS of information are stored in the physical layer. Following are the responsibilities of the physical layer :

• Bit synchronisation: A clock is provided by the physical layer, which allows the bits to be synchronised. This clock controls both the sender and the receiver, ensuring bit-level synchronisation.
• The transmission rate, or the number of bits transferred per second, is likewise defined by the Physical layer.
• Physical topologies: The physical layer defines the arrangement of devices/nodes in a network, such as bus, star, or mesh topologies.
• Transmission mode: The physical layer also specifies how data is passed between the two linked devices. Simplex, half-duplex, and full-duplex transmission modes are available.

Data Link Layer (DLL): The data link layer is in charge of message transport from node to node. The major purpose of this layer is to ensure that data transfers from one node to another through the physical layer are error-free. Following are the responsibilities of data link layer :

• Framing: The data link layer is responsible for framing. It allows a sender to deliver a set of bits to a receiver that are relevant to the receiver. This can be done by attaching unique bit patterns to the frame's beginning and end.
• Physical addressing: After producing frames, the Data link layer adds the sender and/or receiver's physical addresses (MAC addresses) to the header of each frame.
• Error control: The data link layer implements error control by detecting and retransmitting broken or lost frames.
• Flow Control: Because the data rate on both sides must be consistent or the data would be corrupted, flow control coordinates the amount of data that can be transferred before acknowledgment.
• When many devices share a single communication channel, the MAC sub-layer of the data link layer assists in determining which device has control over the channel at any particular time.

Network Layer: The network layer is responsible for data transmission between hosts on different networks. Following are the responsibilities of the network layer :

• Routing: From source to destination, the network layer protocols determine which path is best. Routing is the name for this network layer function.
• The network layer defines an addressing scheme in order to uniquely identify each device on the internetwork. The network layer places the IP addresses of the sender and receiver in the header. An address like this recognises each gadget in a unique and universal way.

Transport Layer: The transport layer delivers services to the application layer while also receiving services from the network layer. Segments are the units of data in the transport layer. Following are the responsibilities of the Transport layer :

• This layer accepts the message from the (session) layer and splits it down into SMALLER parts. A header is attached to each of the segments created. The message is reassembled by the transport layer at the destination station.
• The transport layer header provides a form of address called service point address or port address in order to deliver the message to the relevant process. The transport layer ensures that the message is delivered to the relevant process by supplying this address.

Session Layer: The Session Layer is in charge of establishing connections, maintaining sessions, authenticating users, and ensuring security. Following are the responsibilities of session layer :

• Establishing, maintaining, and terminating a session: The layer enables the two processes to create, use, and terminate a connection.
• Synchronization: This layer allows a process to insert checkpoints into the data that serve as synchronisation POINTS. These synchronisation points aid in the detection of errors so that data may be correctly resynchronized, message ends are not SEVERED prematurely, and data loss is avoided.
• Dialog Controller: The session layer enables two systems to communicate in half-duplex or full-duplex mode.

Presentation Layer: The Presentation Layer is often referred to as the Translation Layer. The data from the application layer is retrieved and processed here so that it may be transmitted across the network in the proper format. Following are the responsibilities of the presentation layer :

• It is responsible for translations such as ASCII to EBCDIC.
• Encryption/decryption: Data encryption is the process of converting data into a different form or coding. The CIPHERTEXT is the encrypted data, and the plain text is the decoded data. When encrypting and decrypting data, a key-value is used.
• Compression: This technique reduces the amount of data that must be transmitted over the network.

Application Layer: The Application layer, which is implemented by network applications, is at the very top of the OSI Reference Model stack of levels. Following are the responsibilities of the application layer :

• This layer also acts as a window for application services to connect to the network and show the information they receive to the user.
• It is also responsible for file transfer access and management.
• It is responsible for mail services.
• It is also responsible for directory services.

The following table lists the differences between new and malloc():

The following table lists the differences between Delete and Truncate SQL commands:

Following are the different types of SQL commands :

• Data Definition Language (DDL): DDL commands are those commands that modify the table's STRUCTURE, such as by adding, deleting, or changing a table. All DDL commands are auto-committed, which MEANS they store all database changes permanently. Example - Create, Drop, Truncate, Alter.
• Data Manipulation Language (DML): The database is modified using DML commands. It is in charge of all database modifications of any kind. The DML command is not auto-committed, which means it cannot preserve all database modifications permanently. They have the potential to be ROLLED back.  Example - Insert, Update, Delete.
• Data Control Language: Any database user can be granted or revoked authority using DCL commands. Example - Grant, Revoke.
• Transaction Control Language (TCL): Transaction Control Language commands are commands that are used to manage transactions in a database. Only DML commands like INSERT, DELETE, and UPDATE can be used with TCL commands. Because these ACTIVITIES are automatically committed to the database, they can't be used while creating or DROPPING tables. Example - Commit, Rollback, Savepoint.
• Data Query Language (DQL): DQL commands are used to fetch data from the database. Example - Select.

• Super key: Super Key is a set of attributes that can be used to uniquely identify a tuple. The super key is created by adding ZERO or more attributes to the candidate key. A candidate key is a super key, but not the other way around.
• Candidate key: A candidate key is the smallest set of attributes that can uniquely identify a tuple. For each tuple, the Candidate Key value is unique and non-null. In relation, there can be more than one candidate key. The candidate key MIGHT be simple (only having one attribute) or composite (CONTAINING multiple attributes).
• Primary key: In relation, there may be more than one candidate key, with one being chosen as the primary key. This primary key is chosen by the database administrator based on the requirements amongst the candidate keys.
• Foreign key: A foreign key is a column or set of columns in a relational database table that connects data from two other tables. It serves as a cross-reference between tables by referencing the primary key of another table and therefore creating a relationship between them.

For example, let US consider tables with the following schema :

Teacher : 

Department : 

Here, for the Teacher table, the following are the DIFFERENT types of keys present :

• The candidate keys can be teacher_id, teacher_phone_number and teacher_aadhar since they all can uniquely identify a record of the table.
• Out of the above three candidate keys, any one of them can be chosen as the primary key. We generally choose teacher_id as the primary key.
• Any of the above candidate keys when grouped with any other key form the super key. For example, teacher_id, teacher_name can together form a super key.
• Teacher_department_id is a foreign key for the Teacher table since it is a primary key in the Department table and it links the two tables.

We can eat a total of 22 CHOCOLATES for Rs. 15. First, we will buy 15 chocolates for 15 rupees since each chocolate costs Re. 1. Now, we have 15 wrappers. We return all the 15 wrappers to the SHOPKEEPER which gives us 5 chocolates (15 / 3 = 5). We eat those five chocolates and return 3 wrappers to the shopkeeper and GET 1 chocolate. We eat that chocolate and again GIVE 3 wrappers which give us ONE chocolate. So, in total, we can have 15 + 5 + 1 + 1 chocolates. 

Example:
Input :
arr = {3, 5, 7, 1, 2, 4, 6}
Output :
{1, 2, 3, 4, 5, 6, 7}

Since we want the sorting algorithm to give the best time complexity in all three cases (that is, best, worst and average), we will implement merge sort to sort the given array of numbers. In merge sort, we divide an array into two HALVES recursively, sort each half and then merge them.

Code:

Output:

Explanation:

In the above code, the function merge() merges the two sorted halves of the array. The function mergeSort() recursively breaks the problem into subproblems, sorts each half and then merges the sorted halves by calling the merge() function. 

Input :
a = 10, b =15
Output :
30
a = 5, b = 7
Output :
35

Let us assume the two numbers are a and b. Then, the two numbers have the following relationship :

or,

Let us take an example to UNDERSTAND better. For a = 10 and b = 15, a * b = 150, LCM(10, 15) = 30, GCD(10, 15) = 5. So, a * b = LCM(a, b) * GCD(a, b).

Code :

Output:

Explanation: 

In the above code, the function findGCD() finds the greatest common divisor of the two numbers a and b. We use the Euclidean algorithm to find the greatest common divisor of the two numbers. The function findLCM() finds the least common multiple of the two numbers.

Multiple inheritances are not allowed by Java using classes. This is because dealing with the complexity that multiple inheritances PRODUCE is quite difficult. For example, 

In the above code, a compilation error is thrown. This is because both the classes Base1 and Base2 contain a definition for the function fun(). This confuses the compiler as to which fun() is being referred to.

Multiple Inheritance causes issues during operations such as casting, constructor chaining, and so on, and the main reason is that we only NEED multiple inheritances in a few cases, thus it's best to leave it out to keep things simple and easy.

However, the main objective of multiple inheritances to inherit from multiple classes can be obtained via interfaces in Java. An interface, LIKE a class, has variables and methods, however, unlike a class, the methods in an interface are abstract by default. The class that implements an interface needs to define the member functions. If a class implements multiple interfaces, or if an interface extends multiple interfaces, multiple inheritances via interface happen. 

For example, the code for the above example using interfaces would be like this:

In the above code, the fun() is not defined in the interfaces Base1 and Base2. They are defined by the classes which implement the interfaces. This leads to no ambiguity and the purpose of multiple inheritances has been solved.

The following table lists the differences between an interface and abstract class:

Following are the advantages of Object-Oriented Programming:

• Instead of needing to start writing code from scratch, we can build programs from standard functioning modules that communicate with ONE another, saving time and increasing productivity.
• The Object-Oriented Programming language allows us to divide the program down into small-sized problems that can be solved quickly (one object at a time).
• The Object-Oriented Programming Language increases programmer EFFICIENCY, improves software quality, and reduces maintenance costs.
• OOPs, concepts can be applied from tiny to large systems.
• It is possible for numerous instances of objects to coexist without interfering with one other
• The data hiding principle aids programmers in CREATING secure programs that are not vulnerable to code in other areas of the program.
• We can MINIMISE duplicate code and increase the use of existing CLASSES by using inheritance.

Object-oriented programming (OOP) is a programming paradigm that organises software design around data, rather than functions and logic. An object is a data field with its own set of properties and behaviour. Object-oriented programming (OOP) focuses on the objects that developers desire to handle rather than the logic that is required to manipulate them. This kind of programming is ideally suited to big, complicated, and frequently updated or maintained projects. Inheritance, hiding, polymorphism, and other real-world concepts are all part of object-oriented programming. The basic goal of OOP is to connect data and the functions that operate on it so that no other part of the code may access it except that function.

Following are the major FEATURES of Object-Oriented Programming:

• Encapsulation: The word "encapsulate" refers to the act of enclosing something. Encapsulation works in OOP in a similar fashion to how a pill "encapsulates" or contains the medication under its coating: by building a protective barrier around the information contained within a class from the rest of the code. In OOP, we encapsulate data and methods that operate on it by combining them into a single unit, the class. We can hide the private information of a class from the outside world and only disclose functionality that is needed to interact with it this way. We say a class is properly enclosed when it prevents calling code from accessing its private data directly.
  • For example, consider a multinational company. There are various sectors in a firm, such as the accounts, finance, and sales departments. The finance department is in CHARGE of all financial transactions and keeps track of all financial data. Similarly, the sales department is in charge of all sales-related activities and keeps track of all sales. Now and then, a circumstance may arise in which a finance official requires complete sales data for a specific month for some reason. In this instance, he is not permitted to view the sales section's data directly. He must first contact ANOTHER officer in the sales department and request that he provide the requested information. Encapsulation is what it is. The data from the sales area, as well as the employees who can change it, are grouped together under the heading "sales section."

• Abstraction: Abstraction is the technique of hiding unnecessary details and displaying only the necessary details. The practice of identifying only the required attributes of an object while discarding the irrelevant information is known as data abstraction. The features and behaviours of an object assist to distinguish it from other THINGS of the same sort, as well as classifying and grouping them.
  • For example, consider an ATM machine. In our daily lives, we all utilise an ATM machine for cash withdrawals, money transfers, retrieving minimum statements, and so on. However, we have no idea what happens inside an ATM machine when you insert an ATM card to execute any type of transaction.

• Inheritance: Inheritance is the technique in Object-Oriented Programming by which one class can acquire all the properties of another class and can even add more properties to its definition. Inheritance, therefore, enforces code reusability. The class whose properties are being inherited is referred to as a base or parent class while the class which inherits the properties of another class is referred to as sub or child class.
  • For example, A child inherits a LOT of physical features from his/ her parents. People often compare whether a particular feature is the same as that of the father or the mother. There are different types of vehicles such as cars, buses, trucks and so on. All of these different types of vehicles can be believed to have inherited all the basic properties of a Vehicle which includes an accelerator, brake and so on.

• Polymorphism: Polymorphism is the technique of using one thing in more than one form. Polymorphism, in other terms, allows you to specify a single interface with various implementations.
  • For example, a person can have different relations with different people around them. A person may be a father to a son, a brother to a sister, a son to a mother and so on. Similarly, a person may behave differently depending on the situation. For example, two people in an office are considered colleagues during work hours, but they can be friends after office hours. When you're in class, you act like a student; when you're in the store, you act like a customer; when you're at home, you act like a son or daughter; here, one person exhibits a variety of behaviours.

Following are the differences between Multiprogramming and Multitasking:

• HTTP: HTTP stands for HYPERTEXT TRANSFER Protocol. HTTP is a set of rules and standards that regulate how information can be sent across the Internet. HTTP establishes communication standards for web browsers and servers. HTTP is a network protocol that runs on top of TCP at the application layer. HTTP employs hypertext structured TEXT to create a logical link between text-containing nodes. It's also known as the "stateless protocol" since each command is conducted separately, without using the last run command as a reference.
• HTTPS: HTTPS is the acronym for HyperText Transfer Protocol Secure. It is a highly advanced and secure HTTP version. For data communication, it uses port 443. Encrypting all communication using SSL, it provides for secure transactions. It's a hybrid of the SSL/TLS and HTTP protocols. It allows a network server to be identified in an encrypted and safe MANNER. HTTPS also enables the server and browser to establish a secure encrypted connection. It provides data security in both directions. This assists you in preventing the theft of potentially sensitive information.