OpenGenus Tech Review Team - OpenGenus IQ: Learn Algorithms, DL, System Design (Page 134)

Overview of Java Servlets

Java Servlets are programs that run on a Web or Application server and act as a middle layer between a requests coming from a Web browser or other HTTP client and databases. We explored Servlet Architecture, Servlet API Hierarchy, Servlet interfaces, Servlet Life Cycle and the life cycle methods

C++

Iterators in C++ STL

Iterators in C++ Standard Template Library are used to point at the memory addresses of STL containers. They are primarily used in sequence of numbers, characters etc. They reduce the complexity and execution time of program.

C++

if else statement in C++

If else statement in C++ are program control statements that are widely used. We explore it and its variants like if else if, nested if else and if statements.

C++

Map in C++ STL

Map in C++ STL is a dictionary like data structure. It is a sequence of (key, value) pair, where only single value is associated with each unique key. It is often referred as associative array.

C++

Reader Writer Problem in C++ using semaphore and monitor

We will focus on solving the Reader Writer problem in C++ by using Semaphores as our first approach and Monitors as our second approach. It is a problem designed to illustrate synchronization within processes.

C Programming

do while loop in C

Do while loop in C is an exit controlled loop and hence, it executes at least once even when the test-expression is false initially. We illustrate the concept and usage in C with different examples

C++

Factory Pattern in C++

Factory method also known as a static class is a creational design pattern, i.e. it is related to object creation. In this we create object without exposing the creation logic to client and the client use the same common interface to create new type of object. Idea is to use a static member function

Data Structures

Leftist Heap

A leftist heap is a modification priority queue implemneted with variant of binary heap. Regarding binary heap, it is always a complete binary tree. It has two main properites Mean Heap Property and Heavy on left side and supports common operations in O(log N) time complexity.

C Programming

While loop in C

Order execution of while loop in C is control variable is initialized, test expression is evaluated, if it evaluates to true, the loop enters the body and it is repeatedly executed, till the expression does not evaluate to false. When the test expression evaluates to false, the loop is exited.

Algorithms

Tile Stacking Problem

We demonstrate how we will reduce the time complexity from O((k+1)^(m+1)) to O(N * M * K) to O(N * M). We have infinite number of tiles of sizes 1 to m. The task is calculate the number of different stable tower of height n with restriction that you can use at most k tiles of each size in the tower

C++

constructor in C++

A constructor is a member function of a class which initializes objects of a class. In C++, Constructor is automatically called when object(instance of class) is created it is considered to be a special member function of the class.

Python

Range Function in Python

Range is an inbuilt function in python that is generally used to create a sequence of numbers. It can accept upto three arguments to modify the output accordingly We will look into its functionalities and any limitations that range has. Let's start from basics and build up our understanding of range

C++

delete operator in C++

In C++, Delete is an operator that is used to destroy array and non-array(pointer) objects which are created by new operator as well as NULL pointers. Using operator overloading, we can delete user defined objects as well

C++

new operator in C++

In C++, the new operator denotes a request for memory allocation on the Heap. If sufficient memory is available, new operator initializes the memory and returns the address of the newly allocated and initialized memory to the pointer variable.

Machine Learning (ML)

Porter Stemmer algorithm

Stemming is the process of reducing a word to its stem that affixes to suffixes and prefixes or to the roots of words lemma. We cover the algorithmic steps in Porter Stemmer algorithm, a native implementation in Python, implementation using Porter Stemmer algorithm from NLTK library and conclusion.

Java

do while loop in Java

A do-while loop is similar to a while loop, except the fact that it is guaranteed to execute at least one time. The do-while loop checks its condition at the bottom of the loop after one time execution of do and hence, is an exit control loop. It is slower than for and while loops in Java

Software Engineering

while loop in Java

A while loop is an entry controlled control flow statement that allows code to be executed repeatedly based on a given condition. In Java, while loop is widely used. On benchmarking the performance, we see that while loop is slower than for loop but is two times faster than do while loop.

Data Structures

Binomial Heap

Binomial Heap is an extension of Binary Heap that provides faster union or merge operation together with other operations provided by Binary Heap. A Binomial Heap is a collection of Binomial trees. Binomial Heap is used to implement priority queues.

Data Structures

Priority Queue

Priority queue is an abstract data type which is like a queue or stack data structure with each element having a priority assigned to it. In priority queue, an element with highest priority assigned is served first, if two elements have same priority then they are served according to enqueue order

Java

Postfix (i++) vs Prefix (++i) increment in Java

i++ is known as postfix increment operation while ++i is known as prefix increment operation. We compare these two operations based on Use/ Program flow, Compiler instruction and Benchmark. We demonstrate that ++i is significantly faster than i++ in Java.

Java

i++ vs i=i+1 in Java

Often, i++ and i=i+1 are considered to be same statements but in Java, both statements work differently internally. We will take a look at The compiler instructions used, Typecasting along with the operations and benchmarking the two operations. We see that i=i+1 is always faster than i++.

Java

for loop in Java

for loop is an entry controlled loop that is widely used in Java programming language. Loops are used to repeat a particular coding task where each repetition follows a particular pattern which can be incorporated in a code. We provided several Java examples to demonstrate the concept

Python

Reading and Writing Text Files in Python

This post will cover how to work with text files specifically in Python. We covered Opening a file, Reading a file: read() and readlines(), Writing to files, keeping track of pointers: tell() and seek(), Closing a file and File attributes

Python

if else statement in Python

We will take a deep look into if else, else if (elif), nested if else and the possible condition statements used in if else in Python. if else is a program control statement and is widely used in almost all programming languages

C++

Classes and Objects in C++

In C++, a class is a mechanism for creating user-defined data types. A class is used to specify the form of an object and it combines data representation. The variables inside class definition are called as data members and the functions are called member functions.