I highly recommend solving problems on spoj.pl (http://www.spoj.pl/ http://www.spoj.pl/). It has a HUGE collection of problems from various competitions, suppor

I highly recommend solving problems on spoj.pl (http://www.spoj.pl/ http://www.spoj.pl/). It has a HUGE collection of problems from various competitions, supports a plethora of languages for coding and the forums are an excellent resource.