### Brain Teasers

# Crime Calls

There has been a murder on a street of bungalows. There are 10 bungalows. Each person who lives in a bungalow knows one unique piece of information. To solve the crime everybody needs to know everything. They decide to share their information by phone.

What is the minimum number of calls that need to be made to solve the crime?

What is the minimum number of calls that need to be made to solve the crime?

### Answer

16Name the 10 people with letters: A, B, C, ... and so on. A through F each call any one of G, H, I, or J (it doesn't matter which one). That makes six calls so far. Then G calls H and I calls J, after which G calls I and H calls J. Now we've used 10 calls, and G, H, I, and J all know everything. Finally, each of A through F is called by someone in G through J - 6 more calls to get everyone knowing everything. 16 calls in all.

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## Comments

Surely J is willing to share his piece of information with I on the 9th call, therefore there is no reason for H to call I a second time, as I already has all the information. That would make the answer 17.

Good catch, Skellum. I've asked Jake to fix the answer. ...although maybe J doesn't like I, so he doesn't feel like sharing his information. I'll bet you didn't think of THAT, did you? ;)

Actually, it can be done in 16 phone calls

(solution not original, I've seen it before).

A through F each call any one of G, H, I, or J (it

doesn't matter who calls whom). Six calls so far.

Then G calls H and I calls J, after which G calls

I and H calls J. Now we've used 10 calls, and G, H,

I, and J all know everything. Finally, each of

A through F is called by someone in G through J -

6 more calls to get everyone knowing everything.

16 calls in all.

(solution not original, I've seen it before).

A through F each call any one of G, H, I, or J (it

doesn't matter who calls whom). Six calls so far.

Then G calls H and I calls J, after which G calls

I and H calls J. Now we've used 10 calls, and G, H,

I, and J all know everything. Finally, each of

A through F is called by someone in G through J -

6 more calls to get everyone knowing everything.

16 calls in all.

sorry i didnt fink like that lol. i'll B more careful in the future

just 10-way call, my friends and i do it all the time... it gets the phone bill up pretty high, but t could be done in one call.

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