64 Horses, 8 tracks, find out the top 4 of the minimum number of races?—— the fastest 10 times, the slowest 11 times;

64 Horses, 8 tracks, find out how many of the top 4 races are the least?

Original answer, reproduced please specify the source: http://www.cnblogs.com/reanote/p/find_4th_in_64horse.html

The first step : All the horses divided into 8 groups, each run once, and then eliminated each group of the last four (8 times);

Step two: Take the first one in each group and then phase out all the horses in the last four groups (1 times):

Analysis: In fact, the red area of the horse can also be eliminated, A1 can be directly promoted;

The third step: A2, A3, A4, B2, B3, C1, C2, D1 eight horses run once, namely: in the remaining need to rank the horse, in addition to B1, the other 8 horses run once (1 times)

Category discussion:

1, if this ranking, B2 or C1 to the top three, then add B1, B1 must be able to the top three, because B1 ranking than B2 and C1 to rely on the front;

The game can be ended; This situation 8+1+1=10 the result;

2, if this ranking, B2 or C1 can not enter the top three, then need to conduct a competition, B1, A2, A3, A4, take the top three:

This situation 8+1+1+1=11 the results.

PS: As for 11 times that situation can be less, temporarily did not think, also did not go further proof.

64 Horses, 8 tracks, find out the top 4 of the minimum number of races?—— the fastest 10 times, the slowest 11 times;