Hey guys,
I found this interview question in a book but couldn't understand it. There's people online saying it doesn't make sense either. Can you guys have a look?
http://questionsininterview.com/welcome-to-questionsininterview-com/problem-solving-interview-questions/the-birthday-problem-interview-question/
Specifically, "By process of elimination, the month is not June or December" doesn't make sense to me. It seems like we can eliminate Jun 7, Jun 4, and Dec 2, but not the rest of the Dec dates.
My thinking is: we can eliminate Jun 7 and Dec 2 because they are unique days. So If C heard the 2nd or the 7th, then he would know the birthday. We can then eliminate June 4th because if "I" knew it were June and "I" know that it's not the 2nd, then it would have to June 4th which violates the condition. But, what if the boss told "me" that it was Dec, and told C that it was the 1st? in the case neither "I" nor C would know the birthday. So, how can we eliminate Dec 1 as a possible birthday?
Thanks!
I found this interview question in a book but couldn't understand it. There's people online saying it doesn't make sense either. Can you guys have a look?
http://questionsininterview.com/welcome-to-questionsininterview-com/problem-solving-interview-questions/the-birthday-problem-interview-question/
Specifically, "By process of elimination, the month is not June or December" doesn't make sense to me. It seems like we can eliminate Jun 7, Jun 4, and Dec 2, but not the rest of the Dec dates.
My thinking is: we can eliminate Jun 7 and Dec 2 because they are unique days. So If C heard the 2nd or the 7th, then he would know the birthday. We can then eliminate June 4th because if "I" knew it were June and "I" know that it's not the 2nd, then it would have to June 4th which violates the condition. But, what if the boss told "me" that it was Dec, and told C that it was the 1st? in the case neither "I" nor C would know the birthday. So, how can we eliminate Dec 1 as a possible birthday?
Thanks!