FAQ - Free resources to train your programming skills


Practice makes perfect - following this age-old saying is very important for a programmer. The more problems we practice solving in a language, the more perfect our skills in that language become.

Therefore, here are a number of free and useful sites - where you can train in a number of real-world problems, learn new algorithms and compete with people across the globe:

  1. CodeWars
  2. CodinGame
  3. Hackerrank
  4. CodeChef
  5. Sphere Online Judge
  6. TopCoder
  7. CodingBat
  8. CheckIO - only Python
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Using a lists of a list in a function (w/range)
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Cool, that helps a lot.


Thanx fot these resources - I think that these resources can help me with studying!


Thanks for the list! Codewars looks really interesting, especially for teaching beginners.


Hey I’m getting an unboundlocalerror and I don’t know how to fix the code

def find_attractions(destination, interests):
destination_index = get_destination_index(destination)
attractions_in_city = attractions[destination_index]
attractions_with_interest =

for attractions in attractions_in_city:
possible_attraction = attraction
attraction_tags = attraction[1]

for intrest in intrests:
  if interest in attraction_tags:

return attractions_with_interest

la_arts = find_attractions(“Los Angeles, USA”, [‘art’])

it says there’s something wrong with the line “attractions_in_city = attractions[destination_index]”