Jump to content
BrainDen.com - Brain Teasers
  • 0


Guest
 Share

Question

You are a policeman in search of a thief hiding in a hotel with 5 rooms-1,2,3,4,5...

The thief changes rooms every night and the policemen can search only one room every morning...

the thief starts from room no. X and follows this rule- the next night he will either go into room no. X+2 or room no. X*2...if the no. exceeds 5 say such a no. is Y then he will go into the room Y-5...

this rule is known to the policemen...what search srategy shud they employ to catch the thief in min. number of days....

i know the ans to the puzzle and i had even vaguely figured out how... but i don't know the exact reason... i think i'll get some help here...

have fun... ^_^

Link to comment
Share on other sites

9 answers to this question

Recommended Posts

  • 0

A question: if the thief is in room five can he stay there? Because 5*2 = 10 and 10 - 5 = 5

no the thief cannot stay in the same room for more than a day...so he will be compelled to follow- 5+2=7

7-5=2...ie go to room no.2

Link to comment
Share on other sites

  • 0

If he is in 1, he must have been in either 3 or 4 yesterday.

If he is in 2, he must have been in either 1 or 5 yesterday.

If he is in 3, he must have been in either 1 or 4 yesterday.

If he is in 4, he must have been in 2 yesterday.

If he is in 5, he must have been in 3 yesterday.

The key here is Room 4 and Room 5 as they have only one possibility.

Possible Rooms    Police Check

1,2,3,4,5                2

1,2,3,5                  3

2,3,4                    4

1,4,5                    4

2,3                      3

4                        4


Link to comment
Share on other sites

  • 0

You are a policeman in search of a thief hiding in a hotel with 5 rooms-1,2,3,4,5...

The thief changes rooms every night and the policemen can search only one room every morning...

the thief starts from room no. X and follows this rule- the next night he will either go into room no. X+2 or room no. X*2...if the no. exceeds 5 say such a no. is Y then he will go into the room Y-5...

this rule is known to the policemen...what search srategy shud they employ to catch the thief in min. number of days....

i know the ans to the puzzle and i had even vaguely figured out how... but i don't know the exact reason... i think i'll get some help here...

have fun... ^_^

Here's what I got. Have no idea if it's most efficient though:

Look in 3 (thief won't be in 5 next day)

Look in 1 (if not in 5 or 1, 2 will be empty next day)

Look in 3 (4 and 5 will be empty next day)

Look in 1 (He can only be in 2 or 3, so next day he can only be in 1, 4, 5)

Look in 1 (Now he can only be on 4 or 5)

Look in 3 (If not there, he has to be in 2)

Look 4 and you got him

So, I get 6 days. This one was fun.

Link to comment
Share on other sites

  • 0

Here's what I got. Have no idea if it's most efficient though:

Look in 3 (thief won't be in 5 next day)

Look in 1 (if not in 5 or 1, 2 will be empty next day)

Look in 3 (4 and 5 will be empty next day)

Look in 1 (He can only be in 2 or 3, so next day he can only be in 1, 4, 5)

Look in 1 (Now he can only be on 4 or 5)

Look in 3 (If not there, he has to be in 2)

Look 4 and you got him

So, I get 6 days. This one was fun.

I see my mistake. Nevermind.....

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...