НП-тешки проблеми — разлика између измена

-{ {{cite book|author=Michael R. Garey and David S. Johnson |year=1979| title = [http://www.amazon.com/Computers-Intractability-NP-Completeness-Mathematical-Sciences/dp/0716710455 Computers and Intractability: A Guide to the Theory of NP-Completeness] | publisher = W.H. Freeman | id = ISBN 978-0-7167-1045-5}} }-