Is there any website available, like spoj.pl/projecteuler.net, that has some test input X for some specified algorithm/data structure Y that you need to impleme

Is there any website available, like spoj.pl/projecteuler.net, that has some test input X for some specified algorithm/data structure Y that you need to implement? Like: Implement a stack in your preferred language! <Explanation of format for test file/input> <Read the following into stdin> This could be really useful to train on your algorithms before you go to spoj/PE.