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Knowing how fast your algorithm runs is extremely important. Often times, you will get asked to determine your algorithm performance in a big-O sense during interview. You will be expected to know how to calculate the time and space complexity... Read more about How to calculate time complexity of an algorithm?

Recently, I ran into this error message in Salesforce where it stated that “LOGIN_MUST_USE_SECURITY_TOKEN: Invalid username, password, security token; or user locked out. Are you at a new location? When accessing Salesforce–either via a desktop client or the API–from outside... Read more about How to fix 'login must use security token' in Salesforce?

Setting up GPG keys on GitHub is important because it allows other to know that you made the commit and not someone else. You, the person with your GitHub profile picture along with your GitHub username and name. Here is... Read more about How to set up GPG key on GitHub?

Ever needed to create a bunch of tables for a newly created user to access in PostgreSQL and see the following error message pop up, ‘permission denied for relation some_table_name’? You are in luck, in this tutorial, I am going... Read more about How to fix 'permission denied for relation some_table_name' in PostgreSQL?

Ever needed to delete a commit completely in GitHub but tried hundred of thousands of tutorials and still does not work? You are in luck! In this tutorial, I am going to teach you guys how to make a GitHub... Read more about How to delete a commit completely in GitHub?

Today, I am going to give a tutorial on how to solve the Fibonacci problem using Dynamic Programming in Java. Before we start to talk about Dynamic Programming. I would like to start briefly on what the Fibonacci problem is.... Read more about Solving the Fibonacci problem using Dynamic Programming in Java

Prerequisite Concepts, Skills and/or Values Experienced with at least one of the programming language ranging from Node.js/Java/C#/Python. Worked with RESTful API. Familiar with Algebra. Understand how HTTP(s)/web request works. AWS account with admin privilege. Introduction Building a scalable and reliable... Read more about Build a scalable, reliable, and inexpensive RESTful API using AWS Lambda that will do the Roman Numerals Conversion

Ever wanted to create a pull request in GitHub but only wished to commit changes that is relevant? You are in luck. In this tutorial, I am going to show you how I would do it. Recently, I tried to... Read more about How to create a GitHub pull request with a specific commits?

Connecting to UVic wifi with Linux for the first time can be a pain in the ass. I literally spent hours trying to figure out how to connect my Linux based laptop to UVic wifi. I thought that it would... Read more about Connecting to UVic wifi with Ubuntu 16.04 LTS

It has been roughly 20 days since the day of a year launch of this blog site. I have been paying attention on the Alexa rank for my site and it has been improved a lot since. The day of... Read more about PoAn (Baron) Chen's Blog global Alexa rank has gone up roughly half a million in 20 days

I started my journey in answering people’s questions on Quora for about half a year now. Quora allows me to learn valuable things from other quorans. The plateform also gives me a place to share my technical knowledges to others.... Read more about I have answered 99 questions on Quora so far

Just like this great article stated that “Combining the Marsyas python bindings with the matplotlib library for plotting in Python creates a great environment for prototyping. In the past few months I have done a lot of Marsyas work using... Read more about Installing Marsyas with Python bindings on Ubuntu 14.04.3 LTS - 64 bits

Ever wonder how you can run one single test with gradlew? Ever get tried of waiting all the tests to be finished? You have came to the right place. Running tests can be a time consuming tasks. Ability to run... Read more about How to run a single test or all tests in a class with gradlew?

Have you ever wanted to replace a git submodules in a repository but don’t know where to start? You are in luck. In this tutorial, I am going to show you how I would do it. It is actually pretty... Read more about How to replace a git submodules in a repository?

Hello everyone, Time really flies. It has been a full year since I blogged on my site. It has been an amazing year so far. Hopefully you have learned a thing or two from the blog that I wrote when... Read more about One Year after PoAn (Baron) Chen's Blog Launch

Have you ever seen this error message error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options. before when you... Read more about How to fix 'error This file requires compiler and library support for the ISO C++ 2011 standard'?

Jekyll is a popular static site generator that is perfect for blogging. In fact, this site uses Jekyll as well. Unlike WordPress, Jekyll does not use/have database at all. Which makes it extremely fast because it does need to make... Read more about How to add Disqus to your Jekyll site?

PDF is an awesome format that allows people to view the document easily across different platform while staying consistent (it will look the same). However, viewing a large PDF on a website could be an issue when the size is... Read more about How to convert a large PDF to HTML?

Today, I am going to show you guys how to use Gulp.js to deploy your site to live through Github. Before we start, I would like to clarify couple of things. In this tutorial, we are making the following assumptions,... Read more about How to use Gulp.js to deploy your site to live through Github?

Cron jobs can be easily removed simply by providing a wrong options. I usually use the command ‘crontab -e’ to add/modify all my scheduled cron jobs. (In fact, I just mistyped e as r haha) Sometimes, I mistyped to option... Read more about How to recover all your deleted cron jobs?

Definition: Mutable object - The object is subject to be changed/altered. Immutable object - The object cannot be changed once created. In some cases, it can be neat to have immutable object as it often leads to a much simpler... Read more about Mutable vs Immutable object in JavaScript

When setting up a web server, there are often sections of the site that you wish to restrict access to. In order to restrict access to a certain page, a password-authentication will be used. In this guide, we will demonstrate... Read more about How to set up password authentication with Apache on Ubuntu 14.04

If you have never play with WordPress, your first thought might be using file_exists(path) in PHP, which is perfectly fine. However, the way how WordPress store the images is different than one might thought. WordPress comes with a default of... Read more about How to check if an image already existed in wp-content/upload directory?

If you have ever play with WordPress, you would know that WordPress is a pretty powerful CMS that allows you to do a lot of cool things. For example, in the setting, you may choose what kind of permalink you... Read more about How to set up pretty url in WordPress?

Before we begin, If you have not yet read the post about how to build a search page in Django with Amazon Dynamodb and React? Part 1, then please read this before you carry on. In this tutorial, we will... Read more about How to build a search page in Django with Amazon Dynamodb and React? Part 2 (Front-end)

Hello everyone, I thought that by creating this tutorial about how to build a search page in Django along with Amazon Dynamodb and React might help you guys to understand more about those trending technologies. First off, I would like... Read more about How to build a search page in Django with Amazon Dynamodb and React? Part 1 (Back-end)

Today, I am going to show you guys how to enable cross-origin resource sharing on an apache server. Before we start, I would like to ask you a question. Have you ever come cross this error message while development? To... Read more about How to enable cross-origin resource sharing on an apache server?

Today, I am going to show you guys how to play mp4 video using hls.js. hls.js is a JavaScript library which implements a HTTP Live Streaming client. It relies on HTML5 video and MediaSource Extensions for playback. What is great... Read more about How to play mp4 video using hls.js?

Today, I am going to show you guys how to add background music in Processing 3.0. Processing is a flexible software sketchbook and a language for learning how to code within the context of the visual arts. One of the... Read more about How to add background music in Processing 3.0?

Today, I am going to show you guys how to take screenshots at different screen sizes using CasperJS. To make it more fun, we are going to take a screenshots on different device with variety screen sizes. For example, iPhone... Read more about How to take screenshots at different screen sizes using CasperJS?

If you have ever play around with server administration, you probably already knew the answer for this. The answer for this question is a BIG yes. It is totally possible to host two website on one server. And, you can... Read more about Is it possible to host two website with different domain name on one server? If yes, how would you do that?

Today, I am going to show you guys how to pass PHP data like an array to your JavaScript file in WordPress. However, you might be thinking why would I need to pass PHP data to the script. For example,... Read more about How to pass PHP data to your script in WordPress?

Today, I am going to show you guys how to login to a site using CasperJS. CasperJS, is a navigation scripting and testing utility for PhantomJS, written in JavaScript. It allows us to test websites a lot like PHPUnit. Imagine... Read more about How to login to a WordPress site using CasperJS?

Today, I am going to show you guys how to programmatically create an account for a user in WordPress. To help you understand clearly, we are going to write a REST API in PHP in the back-end. In the front-end,... Read more about How to programmatically register an account for a user in WordPress?

You probably have heard of Node.js at some points in your life. Maybe it is at stack overflow or somewhere else. No surprise that Node.js became really popular as there are increasing interest in JavaScript on Github. Normally, people use... Read more about How to set up a Node.js application for production on Ubuntu 14.04?

Today, I am going to teach you guys how to build a chat bot using Hubot. So, what is a Hubot? Hubot is a chat bot, modeled after GitHub’s Campfire bot. He is really cool. He can do a lot... Read more about How to build a simple chat bot using Hubot that determine gender based on their first name?

Nowadays, it is no surprise that user will usually receive an email when they first sign up for a new account with a site. It could be a greeting email or a confirmation email. Either way, this should be done... Read more about How to automatically send a welcome email to new user when they sign up for their account in WordPress programmatically?

In this post, we are going to talk about how we can create a simple REST API in PHP and call them in JavaScript using various technologies. For example, using XMLHttpRequest, jQuery AJAX and AngularJS AJAX. In order to create... Read more about How to create a simple REST API in PHP and call them in JavaScript

Well. Finally got around to putting this website together. Neat thing about it - powered by Jekyll and I can use Markdown to author my posts. It actually is a lot easier than I thought it was going to be.... Read more about PoAn (Baron) Chen, Launches Site