http://www.ioi2009.org/index.jsp;jsessionid=0B6696CAD77A789846D13C10D25C1CD8?ln=2&id=363 http://www.ioi2009.org/index.jsp;jsessionid=0B6696CAD77A7898... This i

http://www.ioi2009.org/index.jsp;jsessionid=0B6696CAD77A789846D13C10D25C1CD8?ln=2&id=363 http://www.ioi2009.org/index.jsp;jsessionid=0B6696CAD77A7898... This is the International Informatics Olympiad 2009's page. They have PDFs. Problems range in difficulty, but it does take a lot of thought and time to solve each of the problems.