Software Engineering HashMap in Java In Java, HashMap is a Map based collection class that is used for storing Key and value pairs which is denoted as HashMap<Key, Value>. It does not maintain order of elements, allows one null key, multiple null values, is not thread safe, default size is 16, default load factor is 0.75 JDK1.7, JDK1.8
Data Structures Circular Queue / Ring Buffer / Circular Buffer Circular Queue (Ring Buffer) is also a linear data structure, which follows the principle of FIFO(First In First Out), but instead of ending the queue at the last position, it again starts from the first position after the last, hence making the queue behave like a circular data structure.
Data Structures Implementing Queue using Stack in two ways Queue is an abstract data structure similar to Stacks. Queue is open at both its ends. One end is always used to insert data (enqueue) and the other is used to remove data (dequeue). For implementing queue using stack, one method is to make dequeue costly and other is to make enqueue costly
Data Structures Skip List A skip list is a data structure that is used for storing a sorted list of items with a help of hierarchy of linked lists that connect increasingly sparse subsequences of the items. A skip list allows the process of item look up in efficient manner. The time complexity of operations are O(log N)
Software Engineering Ivan Edward Sutherland: Father of computer graphics Ivan Edward Sutherland is a computer scientist, entrepreneur and Turing Award Winner and is regarded as the Father of Computer Graphics. He is associated with Harvard University, Massachusetts Institute of Technology and Sun Microsystems, Evans and Sutherland and Sutherland Sproull and Associates
Data Structures Octree data structure Octree is a tree data structure where each internal node has 8 children. An octree is generally used to represent relation between objects in a 3-dimensional space. It is used in 3D computer graphics. Octrees are also used for nearest neighbor search which can be done easily in logarithmic time.
Data Structures Palindromic Tree (Eertree) Palindromic tree (Eertree) is a tree based data structure that is specifically used to tackle problems involving palindromes of a string like 'longest palindrome in a string', 'count of plaindromic substrings'. It keeps track of all palindromic substrings of a string in linear time and space
Algorithms Expectation Maximization Clustering Algorithm Expectation Maximization Clustering algorithm is much more robust than K-Means, as it uses two parameters, Mean and Standard Deviation to define a particular cluster. This simple addition of calculating the Standard Deviation, helps the EM algorithm do well in a lot of fail cases of K-Means
Algorithms Mean Shift Clustering Algorithm Mean Shift clustering is an unsupervised clustering algorithm that groups data directly without being trained on labelled data. It is hierarchical in nature. It starts off with a kernel, which is basically a circular sliding window. The bandwidth the radius of this sliding window is pre-decided
Algorithms Cartesian tree sorting Cartesian tree sorting, also called Levcopoulos Petersson algorithm is an adaptive sorting algorithm, i.e. it performs much better on a partially sorted data. It needs two data structures a Cartesian tree and a priority queue. The algorithm here uses min-heap Cartesian tree to give a sorted sequence
Data Structures Fusion Tree Fusion tree is a tree data structure that implements associative array in a known universe size. Fusion trees are used to solve predecessor and successor problem. We have covered sketch, parallel comparison, predecessor and successor and insert operations in O(log N) time and O(N) space complexity
Software Engineering Install Git on any operating system We have covered the commands to install git for the following operating systems: Ubuntu, RHEL, OpenSUSE/ SLES/ SLED, Windows, MacOS and Fedora. Following the installation, you need to configure git to add your username and email id to get started.
Machine Learning (ML) Autoencoder An autoencoder is a neural network that learns data representations in an unsupervised manner. Its structure consists of Encoder, which learn the compact representation of input data, and Decoder, which decompresses it to reconstruct the input data.
Data Structures Doubly Linked List Doubly Linked List has the flexibility of traversing the list in both the ways i.e., forward and backward unlike singly linked list where movement is restricted in forward direction only. Doubly Linked List contains an extra pointer to link the previous node which enables the backward traversing.
Algorithms Activity Selection Problem using Greedy algorithm For activity selection, Dynamic Programming Approach takes O(n^3) time while Greedy Approach takes O(N) time when unsorted and O(n log n) when sorted. It follows Greedy approach as at every step, we make a choice that looks best at the moment to get the optimal solution of the complete problem
Data Structures Implementing Queue using Linked list A queue (First in First out) is an ordered collection of items where the addition of new items happens at one end, called the rear, and removal of existing items occurs at the other end called front. It can be implemented using Linked Lists which brings many advantages over array implementation
Software Engineering for loop in C Loop is a programming concept which is natively supported by C. Loops are used to repeat a particular coding task where each repetition follows a particular pattern which can be incorporated in a code. Example of such a task is printing integers from 1 to 10.
Software Engineering Markdown cheatsheet In this markdown cheatsheet, you will learn about markdown heading, table, list, link, image, code, quote, highlight, bold, italics, strikethrough and others. Markdown is a simple lightweight markup language which is widely used as a formatting language on the web.
Software Engineering Integer datatype in C: int, short, long and long long In C programming language, integer data is represented by its own in-built datatype known as int. It has several variants which includes int, long, short and long long along with signed and unsigned variants The size of int is 4 bytes and range is -2147483648 to 214748364 long long is of 16 bytes
Algorithms Tarjan's Algorithm to find Strongly Connected Components Tarjan's Algorithm is an efficient graph algorithm to find the strongly connected components in a directed graph in linear time by utilizing Depth First Search traversal of a graph. The key idea used is that nodes of strongly connected component form a subtree in the DFS spanning tree of the graph.
Algorithms Cycle Sort Cycle sort is a comparison based sorting algorithm which forces array to be factored into the number of cycles where each of them can be rotated to produce a sorted array with O(N^2) time complexity It is an in-place and unstable sorting algorithm and is optimal in terms of number of memory writes
Algorithms Fibonacci Search Fibonacci search is an efficient search algorithm based on divide and conquer principle using Fibonacci series that can find an element in the given sorted in O(log N) time complexity. It is better than Binary search as it is more cache friendly and uses only addition and subtraction operations.
Data Structures Quadtree Quadtree is a tree data structure which is used to represent 2-dimensional space. It finds major applications in computer graphics where it is used to represent relations between objects in a 2D space and for image compression. We discussed point region (PR) quadtree which store points in a 2D space
Algorithms Bresenham Line Drawing Algorithm Bresenham line drawing Algorithm is a Line Drawing Algorithm which calculates all intermediate points over the interval between start and end points, implemented with integer numbers and integer arithmetic such as addition, subtraction and avoids heavy operations like multiplication and division
Machine Learning (ML) Neural Style Transfer using CNN We demonstrate the easiest technique of Neural Style or Art Transfer using Convolutional Neural Networks (CNN). We use VGG19 as our base model and compute the content and style loss, extract features, compute the gram matrix, compute the two weights and generate the image with the other style
