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Showing posts from January, 2008

Guess a number (Find the floor in building that breaks egg)

Question I have a integer number M in my mind, a number between 1 and N where N is a big number. Chances for M to be any integer between 1 and N are the same. A friend tries to guess this number by asking me to compare M with another number, and I'll answer "your number is bigger", "smaller" or "correct". Another constraint is, his number can be bigger than or equal to M for up to 2 times. What is the strategy to figure out M with least questions? A variation of this question is, in a N stories building, with 2 eggs, find the lowest floor from where egg breaks when it drops to ground. Example answers With only one egg, I can try the 1st floor, the 2nd, 3rd ... until the egg break. This strategy works but it's the worst. Improved answer is, try 2, 4, 6, 8...until one egg breaks. Then use the other egg figure out answer. Or, try 10, 20, 30, 40.... If egg breaks on 60, try 51, 52, 53... This is slightly better than previous answer, but might not be th