title: Numberlink/Flow Game: How to spot NP-Complete problems?
body: <p>I was trying to find a way to solve the problem in the famous game Flow. <a href="http://moh97.us/flow/" rel="nofollow">http://moh97.us/flow/</a></p>
  
  <p>After googling I find out that this is a NP-complete problem. A good solution would make use of heuristics and cuts. How can I spot a NP-complete problem easily? Sometimes when I block, I can't see the obvious solution. When this happens with an NP-complete, it's better to recognise it quickly and move on to the next problem.</p>