Hello!
Today I would like to share interesting online resources which help you improve your programming skills, to be more precise - coding skills.

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One quite interesting is https://app.codility.com/programmers/, an original resource is https://codility.com/.
On this platform, you can learn a particular topic and then apply new knowledge to solve some problems (tasks).

The more important thing is after a solution submission you will get a report about the solution such as correctness, performance, etc… Plus this platform supports many programming languages (Java, Python, C, Go, etc).
You can also participate in challenges https://app.codility.com/programmers/challenges/.
Some of you may be interviewed through this platform (I hope you will be ready after this article!).

Another interesting resource is https://projecteuler.net/.
On this resource you can solve, I would say, more math problems via programming.

Few bits of advice:
1) Do not cheat! Try to solve a problem yourself, then try to improve it and after, check and compare your result with other solutions which were solved by other engineers.

2) Take one problem and try to solve it. I know! Sometimes it takes longer (in my case I spent almost a few days to get a proper solution for one problem).

Conclusion:
By solving this kind of ‘synthetic’ problems you are getting the important thing - an experience, plus when you are back to your ‘real’ work with ‘real’ problems you will find it is kind of easy, for some solution you will begin to recognize a pattern and place for enhancement.
Second, you will keep your tonus as a software engineer (easy to be ready) for a technical interview.