A wee challenge!
05-08-2004, 06:08 AM
#1
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A wee challenge!
Good luck!
There are 4 men who want to cross a bridge. They all begin on the same side. You have 17 minutes to get all of 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 man walks at a different speed. A pair must walk together at a rate of the slower man's pace.
Man 1: 1 minute to cross.
Man 2: 2 minutes to cross.
Man 3: 5 minutes to cross.
Man 4: 10 minutes to cross.
For example, if Man 1 and Man 4 walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Man 4 returns with the flashlight, a total of 20 minutes have passed, and you have failed the mission.
See how quickly you can solve this!
p.s. the flashlight cannot shine a long distance, no one can be carried etc (This is a straight forward problem. There are no tricks.)
ps#2: This question is asked at job interviews at Microsoft.
There are 4 men who want to cross a bridge. They all begin on the same side. You have 17 minutes to get all of 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 man walks at a different speed. A pair must walk together at a rate of the slower man's pace.
Man 1: 1 minute to cross.
Man 2: 2 minutes to cross.
Man 3: 5 minutes to cross.
Man 4: 10 minutes to cross.
For example, if Man 1 and Man 4 walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Man 4 returns with the flashlight, a total of 20 minutes have passed, and you have failed the mission.
See how quickly you can solve this!
p.s. the flashlight cannot shine a long distance, no one can be carried etc (This is a straight forward problem. There are no tricks.)
ps#2: This question is asked at job interviews at Microsoft.
05-08-2004, 08:09 AM
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took somewhere between 10 and 15 mins to figure out....
DONT SCROLL DOWN IF YOU DONT WANT TO KNOW
Start other side total time
1234 -------> 12 (2 mins)
34 <------- 2 (4 mins)
234 -------> 34 (14 mins)
2 <------- 1 (15 mins)
12 -------> 1234 (17 mins)
okay Microsoft, I want a 120,000 salary and stock options, oh and a S2000!
DONT SCROLL DOWN IF YOU DONT WANT TO KNOW
Start other side total time
1234 -------> 12 (2 mins)
34 <------- 2 (4 mins)
234 -------> 34 (14 mins)
2 <------- 1 (15 mins)
12 -------> 1234 (17 mins)
okay Microsoft, I want a 120,000 salary and stock options, oh and a S2000!
05-08-2004, 08:12 AM
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sorry I cant get it to space out properly, hope you can understand if not here is the script version.
men 1 and 2 go across (2 mins total)
man 2 comes back (4 mins toatal)
men 3 and 4 go across (14 mins total)
man 1 comes back (15 mins toatal)
men 2 and 1 go across (17 mins total)
man 1 runs back for keg (18 mins total)
man 1 brings keg back (25 mins toatal)
men get drunk (all night long!!!)
men 1 and 2 go across (2 mins total)
man 2 comes back (4 mins toatal)
men 3 and 4 go across (14 mins total)
man 1 comes back (15 mins toatal)
men 2 and 1 go across (17 mins total)
man 1 runs back for keg (18 mins total)
man 1 brings keg back (25 mins toatal)
men get drunk (all night long!!!)
05-08-2004, 03:59 PM
#7
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Correct
Men 1 & 2 cross 2 minutes
Man 2 goes back 2 minutes
Men 3 & 4 cross 10 minutes
Man 1 goes back 1 minute
Men 1 & 2 cross 2 minutes
Total 17 minutes
Easy as pie right
Men 1 & 2 cross 2 minutes
Man 2 goes back 2 minutes
Men 3 & 4 cross 10 minutes
Man 1 goes back 1 minute
Men 1 & 2 cross 2 minutes
Total 17 minutes
Easy as pie right
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05-08-2004, 09:25 PM
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Men don't need flashlights to cross any damn bridge...
And if only two can cross at the same time logic dictates that the other two are too scared and do not deserve whatever treasures may be found on the other side...
And if only two can cross at the same time logic dictates that the other two are too scared and do not deserve whatever treasures may be found on the other side...
05-08-2004, 09:34 PM
#9
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Originally posted by dispader
Men don't need flashlights to cross any damn bridge...
And if only two can cross at the same time logic dictates that the other two are too scared and do not deserve whatever treasures may be found on the other side...
Men don't need flashlights to cross any damn bridge...
And if only two can cross at the same time logic dictates that the other two are too scared and do not deserve whatever treasures may be found on the other side...
05-08-2004, 10:02 PM
#10
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The real answer is, man one and man two go across, and leave the other two to get killed by the headless horseman. Problem solved, all men across in two minutes max - the dead ones are out of the problem. People who sit around trying to solve stupid riddles are not good workers 