Programming

Implement CPU burner using python

For the modern computers, they mostly have multiple CPU cores. We can use Python's multiprocessing module to automatically get the number of CPU cores. Then we use this module to spawn corresponding processes to generate load on all the CPU cores concurrently. On each CPU core, we can perform arithmetic

Lambda function in Python

A lambda function is a small anonymous function. A lambda function can take any number of arguments, but can only have one expression. Example 1: # Add 10 to argument a, and return the result x = lambda a: a + 10 print(x(5)) # Output: # 15 Example 2: # Multiply argument a and

How to use sorted() and sort() in Python

Using sorted() sorted() is a built-in function in Python. * The original order of values is unchanged once it's called. * It returns an ordered list. numbers = [1, 5, 3, 2, 4] sorted_numbers = sorted(numbers) print(sorted_numbers) print(numbers) # Output: # [1, 2, 3, 4, 5] # [1, 5, 3, 2, 4]

Tree traversal algorithm in Python

Tree traversal (also known as tree search and walking the tree) is a form of graph traversal and refers to the process of visiting (e.g. retrieving, updating, or deleting) each node in a tree data structure, exactly once. Such traversals are classified by the order in which the nodes

Sorting algorithm in Python

Selection sort The selection sort algorithm sorts array by repeatedly finding the minimum element from the unsorted subarray and moving it to the sorted subarray. For ascending order, we can implement the algorithm as below. def selection_sort(my_list): for i in range(len(my_list) - 1): min_

Shadow copy and deep copy in Python

In this post, we'll try to understand the difference between shadow copy and deep copy in Python. We study the copy behavior with list data structure in Python. Problem statement Assuming we have the following list: test_list = [1, 2, [3, 6], 4, 5] We want to create a duplicate

Binary tree traversal - inorder, preorder and postorder

Tree node definition class Node: def __init__(self, val): self.val = val self.left = None self.right = None To build the tree nodes: root = Node(0) n1 = Node(1) n2 = Node(2) root.left = n1 root.right = n2 n3 = Node(3) n4 = Node(4) n1.left = n3 n1.right = n4

Binary search tree in Python

Binary Search Tree is a binary tree data structure which has the following properties: * The left subtree of a node contains only nodes with values smaller than the node. * The right subtree of a node contains only nodes with values greater than the node. * The left and right subtree each

Graph implementation in Python

Intro A graph is a data structure that consists of vertices that are connected via edges. Using an adjacency matrix # implement a graph using adjacency matrix class Graph: def __init__(self, size): self.adj_matrix = [] for i in range(size): self.adj_matrix.append([0 for i in range(size)

Hash Table implementation in Python

Intro Hash Table is a data structure which maps keys to values for highly efficient data search. It stores data in an array by using a hash function to generate a slot to insert the data value. The following are the general steps to insert a key/value pair to

Dynamic array Implementation in Python

In languages like Python, array(aka list) is automatially resizable. The array will grow as you append items. You don't have to resize it manually. In some languages like Java, array comes with fixed length. The size is defined when you create it. When you need a data structure with

StringBuilder implementation in Python

Intro A string is a collection of characters. In Java, StringBuilder class is used to create mutable string. But there isn't a built-in StringBuilder in Python. In Python, string is an immutable object. New memory has to be allocated for every string. In Pythin, there are following ways to implement

Linked List implementation in Python

Intro A linked list is a data structure which represents a sequence of nodes. In a singly linked list, each node points to the next node. In a doubly linked list, each node points to both the next and previous node. To find nth element in the linked list, you

Using Priority Queue in Python

The Priority Queue is implemented with binary heap. To understand how it's implemented, refer to this post. Python provides a built-in implementation of the Priority Queue data structure. For insertion, it uses the put function. The get function dequeues the highest priority item from the queue. To use the Priority

Priority Queue implementation in Python

Priority Queue is an extension of Queue with following properties * each item has a priority associated with it * the item with high priority is dequeued before other item with low priority Binary heap is generally preferred implementation for Priority Queue. It takes time O(log n) to re-heapify the remaining

Min heap and max heap implementation in Python

What is min-heap and max-heap A heap is a data structure based on binary tree. It's designed to efficiently access the smallest or largest element in a collection of items. It follows properties of a complete binary tree. So, it's also known as binary heap. A min-heap(max-heap) is a

Queue implementation in Python

What is queue Like stack, queue is also a linear data structure in which the items are stored in a First-In-First-Out(FIFO)manner. The queue may include the following key functions. * enqueue() - add an item to the end of the queue * dequeue() - remove the front item * size() -

Stack implementation in Python

What is stack Stack is a linear data structure in which the items are in a Last-In-First-Out(LIFO)manner. The stack may include the following key functions. * push() - add an item to the top of the stack * pop() - remove the item at the top * size() - return the

A six-step framework to tackle any system design question

Introduction In the book of System Design Interview by Lewis C. Lin, a six-step framework called PEDALS is introduced to help answer any system design question. PEDALS stand for: * Process requirements * Estimate * Design the service * Articulate the data model * List the architectural components * Scale The systematic method will power you

The complete guide to System Design

The complete guide to System Design in 2022 covers: * What is System Design? * System Design fundamentals * Horizontal and vertical scaling * Microservices * Proxy servers * CAP theorem * Redundancy and replication * Storage * Block storage * File storage * Object storage * Redundant Disk Arrays (RAID) * Message queues * Kafka * File systems * Google File System (GFS) * Hadoop Distributed

AngularJS table creation for dynamic number of columns

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Scale a system to support millions of users

Start from single server Building a large scale system is not one time effort, it should be an iterative process as the user workload increases. The journey could just start with single server and single user request. 1. User access a website through domain name, such as example.com 2.

Set in golang

Go does not have set by default but there is way to imitate it in Go. The following is an example code piece to create "set" in Go by setting a map with empty values. $ cat test.go package main import ( "fmt" ) // Main function func main() { set := make(map[string]

Concepts you should know

Data structure Bloom filter A Bloom filter is a space-efficient probabilistic data structure that is used to test whether an element is a member of a set. For example, checking availability of username is set membership problem, where the set is the list of all registered username. The price we

Solve LeetCode problems in Visual Studio Code

Install the leetcode extension in VS Code Login to LeetCode endpoint with cookie 1. Login to leetcode from Google Chrome 2. In Chrome, Inspect -> Network -> Fetch/XHR 3. Click on any button in leetcode page, and in Inspector to the right under the "Name" tab find and select

Sorting algorithm

In this post, it includes the following sorting algorithms. The code is self explained. * selection sort * insert sort * bubble sort * quick sort * merge sort import java.util.Arrays; public class Sort { public static void selection_sort(int[] arr) { for (int i = 0; i < arr.length - 1; i++) { int min_