Riddle time - U2

klaus

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There are no tricks, this is a straight forward problem.

Allegedly, this is one of the questions for potential Microsoft employees. I must warn you, you can really get caught up trying to solve this problem.

- Reportedly, one guy solved it by writing a C program, although that took him 37 minutes to develop (compiled and ran on the 1st try though).

- Another guy solved it in three minutes.

- A group of 50, at Motorola, couldn't figure it out at all.

See how long it takes you.

Here we go...

"U2" has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge. You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown, etc. Each band member walks at a different speed. A pair must walk together at the rate of the slower man's pace:

- Bono: - 1 minute to cross
- Edge: - 2 minutes to cross
- Adam: - 5 minutes to cross
- Larry: - 10 minutes to cross

For example: if Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission.

Notes: There is no trick behind this. It is the simple movement of resources in the appropriate order. There are two known answers to this problem. This is based on a question that Microsoft gives to all prospective employees.

Note: Microsoft expects you to answer this question in under 5 minutes!
 

klaus

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If you have the answer, DON'T post it right away... lets let everyone think about the it for a while. BTW..it took me more then 3 minutes...and then I gave up. I now know the solution.
 

Tyson

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I did it and thought I had a minute to spare, but turns out I made it in 17 minutes exactly!!

and it was a couple of minutes to solve it.

Look at me, I can fly

MY WEB SITE</font color=red>
<P ID="edit"><FONT SIZE=-1>Edited by Yota_602 on 04/23/02 05:32 PM (server time).</FONT></P>
 

mxjeremy

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DONE. Took me 2 minutes, a pen & paper, I figured out both solutions, and I don't know how you have an extra minute Yota, but PM me with the solution if you do.

I graduated from UCI a couple years ago, and being a Comp Sci, I know a few of Microsoft's interview puzzles, but I have never seen this one before. Lemme know if you want them and I'll see if I can remember them enough to post them up here.
 

rdc

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Good one Klaus... I was about to give up then I got it!!!! I got them across in 14 mins.. So does this mean I get the job???

Tony
<A target="_blank" HREF=http://www.y-not-productions.com>www.y-not-productions.com</A>
 

Tyson

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14 minutes. . .WTF. . .I think you may have added it up wrong.


and Jeremy, I thought I had an extra minute but then I looked down at my paper again, needless to say. .but D'OH!!! I still did it both ways in 17 minutes.

Look at me, I can fly

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rdc

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DOHHHH I did it wrong... I guess it is back to the unemployment line!

Tony
<A target="_blank" HREF=http://www.y-not-productions.com>www.y-not-productions.com</A>
 

rdc

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Okay I figured out how to do it.. Yep it is 17 mins

Tony
<A target="_blank" HREF=http://www.y-not-productions.com>www.y-not-productions.com</A>
 

Tyson

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LOL, that is a tricky little riddle.

I got 1 as well.

a farmer needs to get a fox, chicken, and chicken feed across a lake. He has a small boat that only fits him and 1 object across at a time. How does he get all three things across the lake? and how?

Look at me, I can fly

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rdc

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take the chicken across, come back get the fox and take across, return with chicken, leave chicken and take feed across, go back for chicken...

I got one.. How do you unload a 4.0L motor(complete) out of the back of your truck all alone and you have no engine hoist... J/K that is just something I had to do once that really sucked! But I got it done...

Tony
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Kritter

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not bad klaus. i liked that one.

Kris

"A signature always reveals a man's character -- and sometimes even his name. "
 

klaus

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Answer for those still confused;

Bono + Edge = 2 = 2
Bono = 1 = 3
Larry + Adam = 10 = 13
Edge = 2 = 15
Bono = Edge = 2 = 17

Job done, they all make the concert and i get the job at M$
 

JenDiggityDirt

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The REAL answer to Klaus' questions is: use the flashlight to beat them all until they promise to never ever play any more of their crappy music! The answer to Tyson's questions is: feed the feed to the chicken and the chicken to the fox.

<font color=red>JEN!</font color=red>
 

JenDiggityDirt

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No, i just HATE that horrible band.. And the answer to your question was pure logic at work :) That is the right answer, no?

<font color=red>JEN!</font color=red>
 

Tyson

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farmer takes the chicken across the lake ------------------>

<------------------------------then comes back alone

and gets the fox ----------------------------------------------->

<------------------------then brings back the chicken

and swaps it for the feed, and takes the feed across----->

<-------------------comes back alone to get the chicken

Brings the chicken across the lake---------------------------->

and there ya go!

Look at me, I can fly

MY WEB SITE</font color=red>
 

JCA

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HAHAHAHA Tyson you got it wrong too.

farmer takes the chicken across the lake ------------------>

<------------------------------then comes back alone

and gets the feed ----------------------------------------------->

<------------------------then brings back the chicken

and swaps it for the fox, and takes the fox across----->

<-------------------comes back alone to get the chicken

Brings the chicken across the lake---------------------------->

I was sitting on the shore drinking a cold one and watched the whole thing go down. lol


J.C. Andrews
Andrews Racing
www.andrewsracing.com
 
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