Robert Hansen (RH) posted Mar 8, 2013 7:40 AM: > That is a very hard problem. I managed to figure out > weighings 1 and 3 but could not complete that middle > step. This is not a binary search, it is an > exhaustive search. > > Bob Hansen > That is NOT a "very hard problem" (See below the 'links' to 'binary' and 'exhaustive' searches, for the way I would rather describe it).
It certainly IS a problem that does require (a very little) 'out-of-the-box' thinking to solve (an 'open mind', so to speak).
Joe Niederberger had been able to solve it when he was about 10 years old. I recall I had been able to solve it when I was around 10 or 11 years old - and it was the very first time I ever had an "EUREKA!" moment.
>From your description about 1st weighing,3rd weighing, etc - I believe you have not solved it yet.
For 'out-of-the-box' thinking, the OPMS approach could be quite useful, assuming one has an 'open mind' to begin with - and one is willing to look at and try to understand 'structural models' based on the "CONTRIBUTES TO" and "HINDERS" relationships.
GSC ("Still Shoveling!") Joe Niederberger's post is pasted below. > On Mar 7, 2013, at 4:35 PM, Joe Niederberger > <email@example.com> wrote: > > > By the way, the twelve coin problem is a real > classic -- my father told me it when I was about 10. > > Its easy enough to find a solution using Google, > but as a courtesy to those who want to tough it out - > please don't post a real solution here without the > word "SPOILER" up front! > > > > Cheers, > > Joe N