## Wednesday, February 16, 2011

### Suitcase Locks

A man needs to send important documents to his friend across the country. He buys a suitcase to put the documents in, but he has a problem: the mail system in his country is very corrupt, and he knows that if he doesn't lock the suitcase, it will be opened by the post office and his documents will be stolen before they reach his friend.

There are lock stores across the country that sell locks with keys. The only problem is that if he locks the suitcase, he has no way to send the key to his friend so that the friend will be able to open the lock: if he doesn't send the key, then the friend can't open the lock, and if he puts the key in the suitcase, then the friend won't be able to get to the key.

The suitcase is designed so that any number of locks can be put on it, but the man figures that putting more than one lock on the suitcase will only compound the problem.

After a few days, however, he figures out how to safely send the documents. He calls his friend who he's sending the documents to and explains the plan.

What is the man's plan?

lock the suitcase once and send it..the friend at other end locks the suitcase again and return to u..u remove the lokc and send it again ..u friend removes his lock which he put...

u put lock and send to friend.ur frined puts lock and send back to u ..u remove lock which u had applied ..ur friend removes his lock and opens suitcase

Sean said...

Or you could just send a lock with a number combo, but that would be to easy right?

Shashank Mani said...

@Sharad Good Analysis :) Keep it Up :)

@Sean how does it make sure ? i am not getting you :)

Anonymous said...

How about a simple solution, friend sends a the lock(open). You lock the suitcase using the lock and send him back..

Shashank Mani said...

@Anon , NO Its Not The Solution because , friend can't initiate the process doesn't make sense ? isn't it ? 2nd Only way to send something is via suitcase only , so if friend send something he must send in suitcase with some security else if won't reach to friend who wants to send something to you because of corruption , isn't it ? let me know if i missed something ?

Sania said...

If the man puts the documents and locked it and send to friend then the friend locked it send to the man and the man opened his lock and send to friend(Is it possible that their is two locks);)

Shashank Mani said...

@sania ..yesh that correct answer :)