Algorithms | Misc | Question 12
There are 25 horses among which you need to find out the fastest 3 horses. You can conduct race among at most 5 to find out their relative speed. At no point you can find out the actual speed of the horse in a race. Find out how many races are required to get the top 3 horses.
Explanation: Divide the horses in 5 groups and run 5 races. Take toppers of 5 races and run 6th race more race, the topper of this race will be the fastest horse among all 25. Now run the 7th race among following horses.
1) Second and third fastest horses of 6th race
1) Take the second and third fastest horses of the group which belong to the topper of 6th race.
2) Take the second fastest horse of the group which belongs to second fastest horse of 6th race.
The fastest and second fastest of 7th race are the 2nd and 3rd fastest among all 25.
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