Читать книгу Algorithms For Dummies - John Paul Mueller, John Mueller Paul, Luca Massaron - Страница 38

In some cases, you can’t see the end of a solution process or even know whether you’re winning the war. All you can really do is ensure that you win the individual battles to create a problem solution in hopes of also winning the war. A greedy method to problem solving uses this approach. It looks for an overall solution by choosing the best possible outcome at each problem solution stage.

It seems that winning each battle would necessarily mean winning the war as well, but sometimes the real world doesn’t work that way. A Pyrrhic victory is one in which someone wins every battle but ends up losing the war because the cost of the victory exceeds the gains of winning by such a large margin. You can read about five Pyrrhic victories at https://www.history.com/news/5-famous-pyrrhic-victories. These histories show that a greedy algorithm often does work, but not always, so you need to consider the best overall solution to a problem rather than become blinded by interim wins. The following sections describe how to avoid the Pyrrhic victory when working with algorithms.