title: Bridge crossing puzzle
body: <p>Four men have to cross a bridge at night.Any party who crosses, either one or two men, must carry the flashlight with them. The flashlight must be walked back and forth; it cannot be thrown, etc.  Each man walks at a different speed.  One takes 1 minute to cross, another 2 minutes, another 5, and the last 10 minutes.  If two men cross together, they must walk at the slower man's pace. There are no tricks--the men all start on the same side, the flashlight cannot shine a long distance, no one can be carried, etc.</p>
  
  <p>And the question is What's the fastest they can all get across. I am basically looking for some generalized approach to these kind of problem. I was told by my friend, that this can be solved by Fibonacci series, but the solution does not work for all.</p>
  
  <p>Please note this is not a home work.</p>