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Fair Toss (Posted on 2024-07-02) Difficulty: 3 of 5
Suppose you have one fair coin, that is, a coin that comes up heads half the time and tails half the time.

Show how to use this coin to choose fairly among N people. Solutions using the fewest coin tosses are preferred.

No Solution Yet Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts look at 63 vs 65 | Comment 9 of 12 |
(In reply to re: current thoughts by Steve Herman)

Take a look at 63 vs 65, 2^k - 1 and 2^k + 1.
f(64) = 6

f(63) = 6.10     It's good to be just under a power of 2
f(21) + f(3) = 10.29   Factoring makes it worse
f(7) + f(9) = 10.54
f(7) + f(3) + f(3) = 8.76   best factoring but inflate better

f(65) = 13.78    It's bad to be just over a power of 2
f(13) + f(5) = 9.72   Factoring helps

Try overinflating for 65
7 * 128/(1*65)  = 13.784615384615385 Standard inflate
8 * 256/(3*65)  = 10.502564102564103
9 * 512/(7*65)  = 10.127472527472527  <-- best overinflate
10*1024/(15*65) = 10.502564102564103

  Posted by Larry on 2024-07-02 22:58:29
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