Puzzle:
There are 25 horses, you need to find the fastest 3 horses, up to five existing horse tracks to compete in order to separate the relative speed between them. At any time, you can not find the actual speed is racing (no timers and other tools). The top three horses to find how many games require.
answer:
First, we'll horses divided into five groups, and each group to compete on the track.
In the above table, each row represents five horses in the race. Convenience, using the coordinate (Row, Col) for each horse named. Thus, the first game (first row) in the (1,1), (1,2), (1,3), (1,4) and (1,5) between horses compete five. A second field (line 2) for a match between (2,1), (2,2) and the like horses.
5 assume that the first row of each horse winning the race ((1,5) win first game, (2,5) to win the second game, and so on), the fourth row of each horse winning the first 2 (previous winner of the way and so on), 3 horses each row won the first three. Of course, one of these assumptions are possible, easily understood.
Next, let each row (group) Champion (1,5), (2,5) and five horses duel. Assuming (1,5) in the first place, (2,5) ranked the second, (3,5) third.
The game's fastest horse in the group is (1,5). Whole horse # 2 is likely to be (2,5) or (1,4), in the third row in the whole group of horses can be (3,5), (2,4) or (1,3 ). So five horses will compete.
Therefore, the fastest horse is (1,5). Ranked second and third in the last race in Malaysia are whole groups 2 and 3 horses. Thus, the entire group to determine the fastest of the first, second and third horses minimum number required for the game 7.