perplexus.info :: Algorithms : Guess a number

Guess a number (Posted on 2005-04-14)

If I think of a number between 1 and 1,000, guessing it in 10 yes-no questions is easy... so that's not the puzzle!

Guessing it in 10 yes-no questions, that must be all asked in advance, is also relatively easy... so that's not the puzzle either!

How many questions would you need to guess my number, if you had to ask all questions beforehand, and I also could lie once?

Submitted by Federico Kereki

Rating: 4.3333 (12 votes)

Solution: (Hide)

14 is the right answer -- use 10 questions to get the possible number, and 4 questions to validate the first ten questions.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
Never too late to mention Hamming	Ady TZIDON	2015-10-20 22:01:54
Answer	K Sengupta	2008-12-12 13:02:49
re(2): Unexpected solution	Tristan	2005-04-18 23:18:29
re: Unexpected solution	armando	2005-04-18 21:25:57
re: Unexpected solution	Leming	2005-04-18 00:41:08
Unexpected solution	Tristan	2005-04-15 22:48:02
re: No Subject	armando	2005-04-15 09:04:03
seems impossible	ronen	2005-04-15 08:35:42
No Subject	Leming	2005-04-15 00:13:39
Beginning of a solution	Tristan	2005-04-14 23:26:22
14 are enough	armando	2005-04-14 22:22:21
re: "In Advance"	Erik O.	2005-04-14 22:20:42
guess a number	Marian Elliott	2005-04-14 21:37:38
"In advance"	Old Original Oskar!	2005-04-14 21:36:26
What does "in advance" mean?	Erik O.	2005-04-14 21:29:33
My idea plus one	Leming	2005-04-14 21:03:21
My idea	e.g.	2005-04-14 20:55:30
Close...	Federico Kereki	2005-04-14 20:48:15
Ideas	Charlie	2005-04-14 19:17:58

Please log in:

Login:
Password:
Remember me:

Sign up! \| Forgot password

Search:

Search body:

Forums (1)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (6)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:


perplexus dot info