Break it and make it
You are given 2 eggs. You have access to a 100-story building. Eggs can be very hard or very fragile means it may break if dropped from the first floor or may not even break if dropped from 100th floor. Both eggs are identical. You need to figure out the highest floor of a 100-story building an egg can be dropped without breaking. The question is how many drops you need to make. You are allowed to break 2 eggs in the process.
Problem source: 140 Google Interview Questions.
December 17th, 2009 at 2:38 am
2 eggs, eh? Luxury! Then I’d drop egg 1 from successively the 10th, 20th, 30th,…. floor. If it survived a drop from the 100th floor, my work is done. Otherwise, let’s say that the nth floor was the highest from which egg 1 survived the drop. If egg 1 broke on being dropped from the 10th floor, then n=0. Then I’d drop egg 2 from the n+1st, n+2nd… floor.
December 18th, 2009 at 5:48 am
With Richard’s method, you need 19 drops to know for sure. The 10th drop tells you that it is under 100 stories; the 19th drop would determine if the eggs will survive a 98 or 99 story drop.
Suppose, though, we drop the first egg from the 14th story. If it breaks, we’ll need at most 14 drops. From there, we can drop from the 27th, 39th, 50th, 60th, 69th, 77th, 84th, 90th, 95th, and 99th story. In each case, we’ll have a maximum of 14 drops.
I’m not sure that minimizes the average number of drops, though.
January 7th, 2010 at 10:56 am
wheres the proof that if you drop a egg it wont break from any floor wasted thinking if you ask me . I think the real reason for this question is to see how time you will waste trying to figure out a silly problem .