So, besides on intensifying your knowledge on the concept, you need to actively put it on practice. Therefore these websites are really useful in making it happen.
Lets get straight down to it.
Free Code Camp
FCC mapped out to produce skilled web developer with tons of projects (which probably kind of what differentiate it from other sort of camps).
Pretty nice, right :)
You won't find common algorithm pattern come into practice (binary search, divide and conquer, etc). It will pivot on your ability to solve problems.
Here's one of it's advance algorithm scripting problem:
It's nice to see how they even provide some helpful links you can check on:
The test case you probably wondering, they spring it up so you'd know where you did wrong.
One nice thing about them, is the awesome smooth user interface.
Plenty suggest CoderByte too. They have an organized sections of challenges difficulty, ranges from easy to hard.
One quick preview of it:
There are currently 36 easy challenges, 33 medium challenges, and 45 hard challenges. See if you can solve them all :)
They have point system determined by the accuracy of your code and the time you need to solve it.
One of the best and recommended by many due to it's "war" feel and touch. I'm pretty sure many of you will love Code Wars.
Many of their problems (known as kata) is made by the users, so it keeps growing and growing. In terms of difficulty, you can find it ranges from 1-8. They call it kyu. So, there will be questions mark with 1 kyu until 8 kyu. You will start of with 8 kyu rank, and will level up gradually as you finish the challenges.
One sample question of a 7 kyu kata:
You can define your own test cases:
One awesome thing about this website is that you can see solutions by other "warriors" and vote for which you consider the best practice and clever. You'd find new ways of solving the problems, techniques you wouldn't realize before, which is GREAT!
That's all from me, let me know what you think by leaving a comment!
I'll try to come up with more websites for you to try. Cheers :)