100 doors in a Row  solution incomplete?
Isnt the the 100 doors in a row solution missing a case?
Prime Numbers have only 2 factors  The number itself and 1. For example: 7 has only 2 factors 1, 7. If all the doors are closed at start, then prime number doors will remain closed at the end as well.
Please let me know if this is a valid case.
Thanks!
Shekar
Wednesday, December 10, 2003
That case is essentially covered  that door has an even number of unique divisors  just like the 42nd door in the example (1, 2, 3, 6, 7, 14, 21, 42)  thus it is closed.
Only doors with an odd number of unique divisors will remain open (that being those which are square numbers and thus repeat a divisor).
Lou
Friday, December 12, 2003
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