OpenGenus Tech Review Team - OpenGenus IQ: Learn Algorithms, DL, System Design (Page 129)

Find Maximum Subarray Sum using divide and conquer

We are interested in to find maximum subarray sum (contiguous) of given 1-D array. Array may contain negative and positive numbers which makes this a difficult problem. Brute force will take O(N^2) time while a divide and conquer approach will take O(N log N) time.

Algorithms

Converting Postfix to Infix using Stack

We have explored an algorithm to convert a Postfix expression to Infix expression using Stack. This takes linear time O(N)

Data Structures

Count inversions in an array using Fenwick Tree

Fenwick tree is usually used for range query problems but it can be used to solve the problem of finding the number of inversions in an array efficiently.

Data Structures

Understanding Fenwick tree (Binary Indexed Tree) with Range product

Fenwick tree is a tree based data structure that is widely used to solve range query problems in logarithmic time O(log N) which would otherwise have taken linear time O(N). In this article, we have explained it in depth using the range product query problem.

Software Engineering

Start using Local Storage in JavaScript in Browser

Local storage is a key value storage such that you can store a data as a set of size 2 such as {key, value}. To get the value back, we need to pass key, then we get back value.

Software Engineering

Work with files on the web using FileReader API in JavaScript

FileReader object helps in reading data from a file or a Blob and store it in a JavaScript variable. The read is done asynchronously so as not to block the browser.

Software Engineering

Get started with BLOBs in JavaScript

BLOB (Binary Large OBject) is a data type which can be used to store binary data. We can convert our files and images into binary data and store it using BLOB. They are immutable objects that represent raw data.

Software Engineering

Learn everything about Functions in JavaScript

In this article, you will learn to use functions in JavaScript, how to pass functions as parameters or assign them to variables? and different types of functions like callback and arrow

Software Engineering

Function Pointer in C++

A pointer is a variable that holds the address of another variable. Function pointers are similar and they point to functions. In this article, you will learn What is a function pointer and how to use it? and How to pass a function as an argument to another function?

Software Engineering

Using CSS Selectors to work with specific HTML elements

CSS Selectors are used to define the element(s) to which a particular set of CSS rules should be applied. The following article will take you through different selectors like class selector, attribute selectors, and selector combinations etc.

Software Engineering

Learn to use Dask Dataframes

Dask DataFrame is composed of many smaller Pandas DataFrames that are split row-wise along the index. An operation on a single Dask DataFrame triggers many operations on the Pandas DataFrames that constitutes it.

Problems on Binary Tree

Learn how to traverse a Binary Tree (Inorder , Preorder , Postorder)

In this article we will learn three Depth first traversals namely inorder, preorder and postorder and their use. These three types of traversals generally used in different types of binary tree. In summary, Inorder: left, root, right; Preorder: root, left, right and Postorder: left, right, root

Software Engineering

Understand and use Static members in Java

In this article, you will learn What are static members in Java?, When to use them? and When they can be a problem? Static means only one copy exists for the entire class irrespective of the number of objects that exists for that class.

Software Engineering

Understanding and using Access Specifiers in Java

Access specifiers are utilities/ code features that restrict the access to a particular code feature or data depending upon the source of the code requesting the access. In Java, they are private, public, protected and default.

Software Engineering

Understanding Encapsulation in Java

Encapsulation is an object oriented programming (OOP) implementation technique where we are related data members in a single unit (class) and define member functions to allow indirect and restricted control from the user side.

Software Engineering

Understanding Classes and objects in Java

You will understand Why we need classes?, How to define and use classes in Java?, Structure of classes in Java along with constructors and access specifiers, How to use objects in Java? and Characteristics and attributes of objects along with comparing two objects

Software Engineering

Understanding and working with Third Party Cookies

In this article, you will learn what are third party cookies and how it works?, Cookie profiling, its concern and comparison of third party cookie with first party cookie and a demonstration to build your own page with a third party cookie

Software Engineering

Understanding and working with Cookies

In this article, you will understand the basic idea of cookies, different types of cookies like third party and persistent, how to set, get and delete cookies in JavaScript?, how to view cookies? and how the World looks at it? and a demo to understand the inner workings of cookies

Machine Learning (ML)

Understand Stacked Generalization (blending) in depth with code demonstration

Basic idea behind stacking is to combine the predictions of 2 or more models to get predictions of higher accuracy than the previous submodels. We demonstrate the idea using a code example

Algorithms

Find the maximum sum bitonic subsequence

Given a sequence of numbers in an array A[0.......N]. Find the sum of the maximum bitonic subsequence in the array. naive algorithm will take exponential time O(N * (2^N)) but we can reduced it to O(N^2) using Dynamic programming. We will explore naive approach and go into the dynamic programming

Data Structures

Optimizing a Segment Tree with Lazy Propagation

Lazy propagation is an optimization technique for segment tree to delay some of the update queries so that a set of update queries can be performed more efficiently together and thus, reducing the number of operations performed. The time complexity remain the same.

Software Engineering

Web workers and its API: Run intensive tasks in the background

In some situations where javascript has to run big loops, the browser may prompt error messages. The situation explained above can be handled using Web Workers, who will do all the computationally expensive tasks without interrupting the user interface and typically run on separate threads.

Software Engineering

Page Visibility API: Know when a user is on your page

it was impossible for developers to specify the code that can be executed under any case of unloading a page. In order to solve this problem, Page Visibility API was introduced. The API will listen to any visible change of the page under all the cases, regardless of that, it's on phone or desktop.

Problems on Binary Tree

Algorithm for finding minimum or maximum element in Binary Search Tree【O(log V) / O(V)】

Binary Search Tree is a node-based binary tree data structure and finding the maximum or minimum element take O(log N) in average and can take O(N) in the worst case to O(1) in the best case.

Problems on Binary Tree

Understand everything about Binary Search Tree

Binary search tree is a data structure that quickly allows us to maintain a sorted list of numbers in a tree data structure. It can be used to search for the presence of a number in O(log(n)) time and a simple traversal gives the numbers in sorted order.