64 Horses, 8 tracks, knowledge how many rounds of race to find the fastest 4 horses?

Total Games Required: 8 + 1 + 1 + 1 = 11 field

The idea of solving problems is as follows:

The first step

All the horses are divided into 8 groups, each group of 8, each group run once, and then eliminated each group of the last four, such as (need to match 8 games)

Step Two

Take the first game of each group and then eliminate all the horses in the last four groups, e.g. (1 games required)

The reason: The fastest horse in the group cannot run into the top 4. Then all the horses in the group are not the top 4 horses. It is also possible to know that the fastest runner in this race must be the champion of all horses.

This time the championship has been born, it is the A1, the Blue zone (it does not need to race), and the other may be the fastest three horses can only be in the yellow area (A2,A3,A4,B1,B2,B3,C1,C2,D1, a total of 9 horses)

Note: The following figure in the A1 B1 is not the front of A1 and B1, which is reordered after the race through the above can be known a1>b1>c1>d1 (horse speed)

Step three

As long as the top 9 horses to find the fastest running three horses on it, but now as long as 8 runway, how to do? Then randomly pick 8 horses for a race (one game is needed)

Fourth Step

On top of the game, the top three were selected, but one horse in 9 horses did not run, it may be a potential stock ah, then compared with the top three, the four horses than one, the first three elected. Finally add the championship, the fastest four horses were born!!! (Need a game)

64 Horses, 8 tracks, knowledge how many rounds of race to find the fastest 4 horses?