I took these tasks from the great book "Cracking The Coding Interview" written by Gayle Laakmann McDowell.
You can see a links below with language tag and progress bar.
Each section was solved in a specific programming language. Progress means how far I have come, what tasks have been completed.
There you can find a readme files with implementation details. Each task has a naive (mine) and an optimized (described in the book) implementation. Does this mean that the naive will always be worse than the optimized one? - No, it's just mine own solution. First, I try to solve the problem on my own, this is how a naive implementation was created, then I read the solution described in the book and implement it in a specific language. Sometimes I have exactly the same point of view, then the task will have one solution.
You also be able to clone this project, compile and run my solutions.