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Posted on Aug 12, 2021 • Updated on Sep 12, 2021

11 Websites To Practice You Coding And Your Problem Solving Skills

11 websites to practice your coding and problem-solving skills.

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10 websites to practice coding problems: Our picks

Whether you're just starting out as a coder or want to advance your coding skills, tackling programming problems is part of the plan. 

Convenient, free, and even fun, coding problem websites challenge your abilities with individual exercises, friendly challenges, and insightful assessments.

Practicing your coding through these websites may increase your knowledge, build your skills, and prepare you for programming job interviews. 

Top websites for practicing your coding skills

Should a humanities major learn to code.

Can a humanities student learn coding? Absolutely. Coding is not strictly for STEM students — it can benefit you no matter your degree.

How hard is it to learn coding ? Starting from scratch can be difficult, but coding challenges designed to test and advance your skills may help. We rounded up 10 great websites for coding problems and listed them alphabetically for you. 

Each website offers a collection of resources for learning coding or advancing what you already know. 

1. CodeChef

CodeChef lets you choose among thousands of problems to practice skills like sorting, data structures, and dynamic programming. Problems are sortable by difficulty. Code Chef's practice problems allow you to answer in one of over 50 programming languages as you prepare for its internal or external monthly contests. 

CodeChef offers self-guided learning opportunities and mentoring programs alongside a community of coders, coding bootcamps, and tech certification programs. 

2. Coderbyte

Designed for coding practice and improvement, Coderbyte offers code challenges and courses aimed at helping you prepare for job interviews. 

Coderbyte had over three million solutions with challenges in more than 25 languages. Starter courses in algorithms, JavaScript, Ruby, and Python accompany interview kits and career resources. 

You can sign up for a free challenge and free trial. A monthly subscription to Coderbyte costs $35 and an annual subscription is $150. Both give you access to all of Coderbyte's resources. 

3. Codewars

Launched in 2012, Codewars provides practice kata, or small coding exercises, that you advance through as you build your skills. Codewars' kata are available in nearly 60 programming languages and in levels from beginner to advanced.

You can develop your own kata, engage with the Codewars community, and master one or multiple languages in the process. Feedback and creative learning facilitate creative thinking and innovation among Codewars' users. Codewars offers resources for educators and companies as well. 

4. CodinGame

With more than 25 supported languages, CodinGame provides challenge-based programming training through games, puzzles, and competitions. 

CodinGame's resources let you build your programming abilities, learn new concepts, and interact with fellow coders through easy, medium, hard, and very hard exercises.

CodeinGame's leaderboard and prizes earn you recognition from your peers and track your progress. Free live streams, blogs, and discussion forums for developers accompany sourcing, screening, and retention programs for recruiters. 

5. Geektastic

With human-reviewed technical assessments, Geektastic lets companies customize coding challenges for talent acquisition and engineering team training. If you have coding experience, you can join Geektastic's reviewer community to create and test those challenges — and get paid to review candidates' performance. 

Code challenges are offered in Java, Python, and PHP. Geektastic also offers skills assessments in Java, Javascript, and basic coding. Joining as a developer comes with no cost, while flexible pricing accommodates businesses of any size. 

6. HackerRank

HackerRank serves as a technical interview platform, but also provides coding practice to over 18 million users. Challenges offered by HackerRank cover topics including algorithms, Java, Python, Ruby, and data structures. 

HackerRank's challenges allow you to test your code, debug it, and win one of its sprint, company, language, or timed challenges. You can also earn certifications in specific skills or complete interview preparation kits. Pricing ranges from $25/month for interview content to $819/month team subscriptions.

7. LeetCode

LeetCode provides more than 2,250 practice problems to its programmer community. Individual challenges in topics like algorithms, database structures, and dynamic programming accompany entire study plans. 

LeetCode's programming skills study plan integrates three modules offered at easy, medium, or hard difficulty levels. LeetCode supports 14 programming languages and houses a playground tool to help you test, debug, and write code. 

Sign-up is free. LeetCode Premium offers access to additional tools and premium content for a monthly subscription of $35 or an annual fee of $159. 

8. Project Euler

Named for mathematician Leonhard Euler, Project Euler began in 2001. Recent and archival content is available for registered users at no cost. 

Project Euler offers computational programming problems combining mathematics with computer and programming skills. With 108 programming languages and more than one million users, Project Euler provides problems with varying difficulty.

Sphere Online Judge, or SPOJ , trains users to code and build efficient algorithms through more than 20,000 practice problems. Scoring categories for problems include challenges, tutorials, and riddles. Rankings and a status board accompany running contests that support more than 45 programming languages and compilers. 

SPOJ offers a flexible testing system to automatically assess user-submitted programs. Users can design their own contests or take part in an online course at all programming levels, but it is ideal for students.

10. TopCoder

TopCoder's community of designers, developers, data scientists, and competitive programmers build their skills, show their expertise, and earn money as they improve their coding abilities. TopCoder pays individuals for their work, sells it to corporate clients, and hosts competitions designed to highlight top coding talent worldwide.

Customers use TopCoder to hire freelancers on-demand, set challenges for the coding community, and find teams for projects.

This article was reviewed by Monali Mirel Chuatico

In 2019, Monali Mirel Chuatico graduated with her bachelor's in computer science, which gave her the foundation that she needed to excel in roles such as data engineer, front-end developer, UX designer, and computer science instructor.

Monali is currently a data engineer at Mission Lane. As a data analytics captain at a nonprofit called COOP Careers , Monali helps new grads and young professionals overcome underemployment by teaching them data analytics tools and mentoring them on their professional development journey.

Monali is passionate about implementing creative solutions, building community, advocating for mental health, empowering women, and educating youth. Monali's goal is to gain more experience in her field, expand her skill set, and do meaningful work that will positively impact the world.

Monali Mirel Chuatico is a paid member of the Red Ventures Education Integrity Network. 

Last reviewed April 21, 2022.

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How to think like a programmer — lessons in problem solving

by Richard Reis

If you’re interested in programming, you may well have seen this quote before:

“Everyone in this country should learn to program a computer, because it teaches you to think.” — Steve Jobs

You probably also wondered what does it mean, exactly, to think like a programmer? And how do you do it??

Essentially, it’s all about a more effective way for problem solving .

In this post, my goal is to teach you that way.

By the end of it, you’ll know exactly what steps to take to be a better problem-solver.

Why is this important?

Problem solving is the meta-skill.

We all have problems. Big and small. How we deal with them is sometimes, well…pretty random.

Unless you have a system, this is probably how you “solve” problems (which is what I did when I started coding):

• Try a solution.
• If that doesn’t work, try another one.
• If that doesn’t work, repeat step 2 until you luck out.

Look, sometimes you luck out. But that is the worst way to solve problems! And it’s a huge, huge waste of time.

The best way involves a) having a framework and b) practicing it.

“Almost all employers prioritize problem-solving skills first.

Problem-solving skills are almost unanimously the most important qualification that employers look for….more than programming languages proficiency, debugging, and system design.

Demonstrating computational thinking or the ability to break down large, complex problems is just as valuable (if not more so) than the baseline technical skills required for a job.” — Hacker Rank ( 2018 Developer Skills Report )

Have a framework

To find the right framework, I followed the advice in Tim Ferriss’ book on learning, “ The 4-Hour Chef ”.

It led me to interview two really impressive people: C. Jordan Ball (ranked 1st or 2nd out of 65,000+ users on Coderbyte ), and V. Anton Spraul (author of the book “ Think Like a Programmer: An Introduction to Creative Problem Solving ”).

I asked them the same questions, and guess what? Their answers were pretty similar!

Soon, you too will know them.

Sidenote: this doesn’t mean they did everything the same way. Everyone is different. You’ll be different. But if you start with principles we all agree are good, you’ll get a lot further a lot quicker.

“The biggest mistake I see new programmers make is focusing on learning syntax instead of learning how to solve problems.” — V. Anton Spraul

So, what should you do when you encounter a new problem?

Here are the steps:

1. Understand

Know exactly what is being asked. Most hard problems are hard because you don’t understand them (hence why this is the first step).

How to know when you understand a problem? When you can explain it in plain English.

Do you remember being stuck on a problem, you start explaining it, and you instantly see holes in the logic you didn’t see before?

Most programmers know this feeling.

This is why you should write down your problem, doodle a diagram, or tell someone else about it (or thing… some people use a rubber duck ).

“If you can’t explain something in simple terms, you don’t understand it.” — Richard Feynman

Don’t dive right into solving without a plan (and somehow hope you can muddle your way through). Plan your solution!

Nothing can help you if you can’t write down the exact steps.

In programming, this means don’t start hacking straight away. Give your brain time to analyze the problem and process the information.

To get a good plan, answer this question:

“Given input X, what are the steps necessary to return output Y?”

Sidenote: Programmers have a great tool to help them with this… Comments!

Pay attention. This is the most important step of all.

Do not try to solve one big problem. You will cry.

Instead, break it into sub-problems. These sub-problems are much easier to solve.

Then, solve each sub-problem one by one. Begin with the simplest. Simplest means you know the answer (or are closer to that answer).

After that, simplest means this sub-problem being solved doesn’t depend on others being solved.

Once you solved every sub-problem, connect the dots.

Connecting all your “sub-solutions” will give you the solution to the original problem. Congratulations!

This technique is a cornerstone of problem-solving. Remember it (read this step again, if you must).

“If I could teach every beginning programmer one problem-solving skill, it would be the ‘reduce the problem technique.’

For example, suppose you’re a new programmer and you’re asked to write a program that reads ten numbers and figures out which number is the third highest. For a brand-new programmer, that can be a tough assignment, even though it only requires basic programming syntax.

If you’re stuck, you should reduce the problem to something simpler. Instead of the third-highest number, what about finding the highest overall? Still too tough? What about finding the largest of just three numbers? Or the larger of two?

Reduce the problem to the point where you know how to solve it and write the solution. Then expand the problem slightly and rewrite the solution to match, and keep going until you are back where you started.” — V. Anton Spraul

By now, you’re probably sitting there thinking “Hey Richard... That’s cool and all, but what if I’m stuck and can’t even solve a sub-problem??”

First off, take a deep breath. Second, that’s fair.

Don’t worry though, friend. This happens to everyone!

The difference is the best programmers/problem-solvers are more curious about bugs/errors than irritated.

In fact, here are three things to try when facing a whammy:

• Debug: Go step by step through your solution trying to find where you went wrong. Programmers call this debugging (in fact, this is all a debugger does).

“The art of debugging is figuring out what you really told your program to do rather than what you thought you told it to do.”” — Andrew Singer

• Reassess: Take a step back. Look at the problem from another perspective. Is there anything that can be abstracted to a more general approach?

“Sometimes we get so lost in the details of a problem that we overlook general principles that would solve the problem at a more general level. […]

The classic example of this, of course, is the summation of a long list of consecutive integers, 1 + 2 + 3 + … + n, which a very young Gauss quickly recognized was simply n(n+1)/2, thus avoiding the effort of having to do the addition.” — C. Jordan Ball

Sidenote: Another way of reassessing is starting anew. Delete everything and begin again with fresh eyes. I’m serious. You’ll be dumbfounded at how effective this is.

• Research: Ahh, good ol’ Google. You read that right. No matter what problem you have, someone has probably solved it. Find that person/ solution. In fact, do this even if you solved the problem! (You can learn a lot from other people’s solutions).

Caveat: Don’t look for a solution to the big problem. Only look for solutions to sub-problems. Why? Because unless you struggle (even a little bit), you won’t learn anything. If you don’t learn anything, you wasted your time.

Don’t expect to be great after just one week. If you want to be a good problem-solver, solve a lot of problems!

Practice. Practice. Practice. It’ll only be a matter of time before you recognize that “this problem could easily be solved with <insert concept here>.”

How to practice? There are options out the wazoo!

Chess puzzles, math problems, Sudoku, Go, Monopoly, video-games, cryptokitties, bla… bla… bla….

In fact, a common pattern amongst successful people is their habit of practicing “micro problem-solving.” For example, Peter Thiel plays chess, and Elon Musk plays video-games.

“Byron Reeves said ‘If you want to see what business leadership may look like in three to five years, look at what’s happening in online games.’

Fast-forward to today. Elon [Musk], Reid [Hoffman], Mark Zuckerberg and many others say that games have been foundational to their success in building their companies.” — Mary Meeker ( 2017 internet trends report )

Does this mean you should just play video-games? Not at all.

But what are video-games all about? That’s right, problem-solving!

So, what you should do is find an outlet to practice. Something that allows you to solve many micro-problems (ideally, something you enjoy).

For example, I enjoy coding challenges. Every day, I try to solve at least one challenge (usually on Coderbyte ).

Like I said, all problems share similar patterns.

That’s all folks!

Now, you know better what it means to “think like a programmer.”

You also know that problem-solving is an incredible skill to cultivate (the meta-skill).

As if that wasn’t enough, notice how you also know what to do to practice your problem-solving skills!

Phew… Pretty cool right?

Finally, I wish you encounter many problems.

You read that right. At least now you know how to solve them! (also, you’ll learn that with every solution, you improve).

“Just when you think you’ve successfully navigated one obstacle, another emerges. But that’s what keeps life interesting.[…]

Life is a process of breaking through these impediments — a series of fortified lines that we must break through.

Each time, you’ll learn something.

Each time, you’ll develop strength, wisdom, and perspective.

Each time, a little more of the competition falls away. Until all that is left is you: the best version of you.” — Ryan Holiday ( The Obstacle is the Way )

Now, go solve some problems!

And best of luck ?

Special thanks to C. Jordan Ball and V. Anton Spraul . All the good advice here came from them.

Thanks for reading! If you enjoyed it, test how many times can you hit in 5 seconds. It’s great cardio for your fingers AND will help other people see the story.

If this article was helpful, share it .

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How the web works

• Overview: Getting started with the web

How the web works provides a simplified view of what happens when you view a webpage in a web browser on your computer or phone.

This theory is not essential to writing web code in the short term, but before long you'll really start to benefit from understanding what's happening in the background.

Clients and servers

Computers connected to the internet are called clients and servers . A simplified diagram of how they interact might look like this:

• Clients are the typical web user's internet-connected devices (for example, your computer connected to your Wi-Fi, or your phone connected to your mobile network) and web-accessing software available on those devices (usually a web browser like Firefox or Chrome).
• Servers are computers that store webpages, sites, or apps. When a client device wants to access a webpage, a copy of the webpage is downloaded from the server onto the client machine to be displayed in the user's web browser.

The other parts of the toolbox

The client and server we've described above don't tell the whole story. There are many other parts involved, and we'll describe them below.

For now, let's imagine that the web is a road. On one end of the road is the client, which is like your house. On the other end of the road is the server, which is a shop you want to buy something from.

In addition to the client and the server, we also need to say hello to:

• Your internet connection : Allows you to send and receive data on the web. It's basically like the street between your house and the shop.
• TCP/IP : Transmission Control Protocol and Internet Protocol are communication protocols that define how data should travel across the internet. This is like the transport mechanisms that let you place an order, go to the shop, and buy your goods. In our example, this is like a car or a bike (or however else you might get around).
• DNS : Domain Name System is like an address book for websites. When you type a web address in your browser, the browser looks at the DNS to find the website's IP address before it can retrieve the website. The browser needs to find out which server the website lives on, so it can send HTTP messages to the right place (see below). This is like looking up the address of the shop so you can access it.
• HTTP : Hypertext Transfer Protocol is an application protocol that defines a language for clients and servers to speak to each other. This is like the language you use to order your goods.
• Code files : Websites are built primarily from HTML, CSS, and JavaScript, though you'll meet other technologies a bit later.
• Assets : This is a collective name for all the other stuff that makes up a website, such as images, music, video, Word documents, and PDFs.

So what happens, exactly?

When you type a web address into your browser (for our analogy that's like walking to the shop):

• The browser goes to the DNS server, and finds the real address of the server that the website lives on (you find the address of the shop).
• The browser sends an HTTP request message to the server, asking it to send a copy of the website to the client (you go to the shop and order your goods). This message, and all other data sent between the client and the server, is sent across your internet connection using TCP/IP.
• If the server approves the client's request, the server sends the client a "200 OK" message, which means "Of course you can look at that website! Here it is", and then starts sending the website's files to the browser as a series of small chunks called data packets (the shop gives you your goods, and you bring them back to your house).
• The browser assembles the small chunks into a complete web page and displays it to you (the goods arrive at your door — new shiny stuff, awesome!).

Order in which component files are parsed

When browsers send requests to servers for HTML files, those HTML files often contain <link> elements referencing external CSS stylesheets and <script> elements referencing external JavaScript scripts. It's important to know the order in which those files are parsed by the browser as the browser loads the page:

• The browser parses the HTML file first, and that leads to the browser recognizing any <link> -element references to external CSS stylesheets and any <script> -element references to scripts.
• As the browser parses the HTML, it sends requests back to the server for any CSS files it has found from <link> elements, and any JavaScript files it has found from <script> elements, and from those, then parses the CSS and JavaScript.
• The browser generates an in-memory DOM tree from the parsed HTML, generates an in-memory CSSOM structure from the parsed CSS, and compiles and executes the parsed JavaScript.
• As the browser builds the DOM tree and applies the styles from the CSSOM tree and executes the JavaScript, a visual representation of the page is painted to the screen, and the user sees the page content and can begin to interact with it.

DNS explained

Real web addresses aren't the nice, memorable strings you type into your address bar to find your favorite websites. They are special numbers that look like this: 192.0.2.172 .

This is called an IP address , and it represents a unique location on the web. However, it's not very easy to remember, is it? That's why the Domain Name System was invented. This system uses special servers that match up a web address you type into your browser (like "mozilla.org") to the website's real (IP) address.

Websites can be reached directly via their IP addresses. You can use a DNS lookup tool to find the IP address of a website.

Packets explained

Earlier we used the term "packets" to describe the format in which the data is transferred between the client and server. What do we mean here? Basically, when data is sent across the web, it is sent in thousands of small chunks. There are multiple reasons why data is sent in small packets. They are sometimes dropped or corrupted, and it's easier to replace small chunks when this happens. Additionally, the packets can be routed along different paths, making the exchange faster and allowing many different users to download the same website at the same time. If each website was sent as a single big chunk, only one user could download it at a time, which obviously would make the web very inefficient and not much fun to use.

• How the Internet works
• HTTP — an Application-Level Protocol
• HTTP: Let's GET It On!
• HTTP: Response Codes

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