[HN Gopher] 12 Coins in Verse: Genius solution of twelve balls a...
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       12 Coins in Verse: Genius solution of twelve balls and a scale
       problem
        
       Author : vismit2000
       Score  : 23 points
       Date   : 2024-08-07 05:05 UTC (4 days ago)
        
 (HTM) web link (www.cut-the-knot.org)
 (TXT) w3m dump (www.cut-the-knot.org)
        
       | macrael wrote:
       | Wow I didn't know there was a solution where you always weigh
       | 4v4. I've only ever solved it with weighings that eliminate
       | coins, never with a sum at the end
        
         | contravariant wrote:
         | Makes me wonder if there's an obvious way to see how it works.
         | Technically you could just go from the table at the end of this
         | article and keep swapping until you end up with a system that
         | puts an equal number of coins at both ends.
         | 
         | Though the system uses 12 out of the 13 possible pairs (and
         | never EEE, for obvious reasons) and I'm not sure if it matters
         | which one you leave out. (for those keeping track LRL/RLR
         | doesn't occur, but this could equivalently have been any of the
         | 4 pairs without an E)
         | 
         | Personally I was quite happy to solve it by figuring out the
         | sub-problem of finding a fake coin out of 4 possible fakes and
         | one real coin, and then reducing the 12 coin problem to that.
        
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       (page generated 2024-08-11 23:01 UTC)