#61




Re: Brain Teasers & Riddles
Quote:
Quote:

#62




Re: Brain Teasers & Riddles
600,000 ?

#63




Re: Brain Teasers & Riddles

#64




Re: Brain Teasers & Riddles
Yeah, it was a bit unclear, but yours seemed closest.

#65




Re: Brain Teasers & Riddles
Once again, I'm invoking the 24 hour rule.
Next challenge: There are 25 horses and the race track only allows 5 horses to race at a given time. Given that there is no stop watch available your task is to determine the fastest 3 horses. Assume that each horses' speed is constant in different races, what is the minimum number of races to determine the fastest 3? 
#66




Re: Brain Teasers & Riddles
Oooh, comptuer science... lol.
Eight races. 
#67




Re: Brain Teasers & Riddles
Not correct.
There is a way to do it with less. You work for Microsoft or something? 
#68




Re: Brain Teasers & Riddles
Quote:
My answer was the product of modified "merge sort" (though, merge sort is not always optimal, as we're apparently seeing here... ) 
#69




Re: Brain Teasers & Riddles
Oh, scratch it. I know the answer, but I won't say, since I already screwed the pooch. I shouldn't have been using any sorting at all...
I arrived at the answer I did by thinking of the maximum number that you could eliminate in any given race  for the first five races, you eliminate two each for a total of fifteen. Then, you can eliminate 4 horses in each subsequent race for a total of 11, then 7, then 3 horses remaining after 8 races. I figured I had to be right since the math lined up so nicely. Thinking man's error  life isn't a standardized test 
#70




Re: Brain Teasers & Riddles
I can get it down to 7.
Races 15: Divide horses into sets of 5 (AE) and race them, eliminate all fourth and fifth place finishers immediately. We can now rank the 3 remaining horses of each group internally. down to 15 horses. Race 6: Race the winners of the first 5 races. Lets say the winner of group A places first, the winner of group B second, the winner of group C third...etc. Eliminate groups D and E entirely. Eliminate all but the fastest horse (the one who just raced) in group C.  down to 7 horses. We know the winner of the last race (the fastest in group A) is THE fastest horse, so we can set him aside; now we just need to find the other two. We also know that the slowest horse of the 3 in group B cannot be among the 3 fastest, so we eliminate him. That gives us 5 horses left to race. Race 7: Race those five (the 2nd and 3rd place finishers from group A, the 1st and 2nd place finishers from group B, and the only remaining horse in group C). The top two finishers and the horse we set aside earlier are the 3 fastest. 
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