rainbow@ihuxe.UUCP (05/30/84)
Lets forget about these simple cases of 12 and 13 coins. Lets get right into the toughest one. 26 coins. You have a balance usable three times. You must determine which one of them is counterfeit and if its lighter or heavier than the standard. And if that isnt tough enough, lets try 80 coins and four weighings.. AS for the solution of 13 coins(the extra coin known to be good is irrelevant to the problem), any division of coins works. ie 6-6-1 or 5-5-3 or 4-4-5 or 3-3-7. This is because 7 coins can be solved in two steps which I will leave to the reader to answer.