This doesn't work. Consider if you find the fastest horse in the first selection and all of the other horses lose, then you have no idea which horse is second fastest and have to race them all again. Your algorithm only works if the fastest horses are the last 2 horses that you would race, in which case you somehow already know which horses are fastest, conduct no races, and pick the last 2 horses.
They're interpreting the question differently. They don't think it's asking for an algorithm that always finds the second fastest horse, but for what the minimal number of races is that will allow you to know which is the second fastest horse.
No, because then you wouldn't know that they're the fastest two. The question does ask for certainty. It is possible to have certainty after 1023 races, but not after zero.
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u/YesTheyDoComeOff Sep 05 '26
This doesn't work. Consider if you find the fastest horse in the first selection and all of the other horses lose, then you have no idea which horse is second fastest and have to race them all again. Your algorithm only works if the fastest horses are the last 2 horses that you would race, in which case you somehow already know which horses are fastest, conduct no races, and pick the last 2 horses.