Can You Solve These Challenging Microsoft Interview Riddles?

[Rahmuss]

Err nope,
(warning : spoiler)

Assume a,b,c,d are on the left side.
Objective -> a,b,c,d to go to right side in minimum time
Constraints -> Just one flashligh, flashlight necessary to cross and bridge can balance at the max 2 people
a(1 min,flashlight),b(2 min) go right --> 2 mins
a(1 min,flashlight) goes left --> 1 mins
c(5 min,flashlight),d(10 min) go right -> 10 mins
b(2 min,flashlight) goes left --> 2 mins
a(1 min,flashlight),b(2 min) go right --> 2 mins
Total -> 2+1+10+2+2 = 17 mins
[/Color]

-- AI

The problem is that "nobody can go alone".

 

[Rahmuss]

this was my solution..i'm not going to white it because its a matter of the way you interpret the question. 10min carries flashlight.5+2+1+1+1=8 = 10.

This is a good thought. When it says that they can't go alone does that mean that they have to be on the bridge the same time as someone else? If that's the case then I think that works out well.

 

[Rahmuss]

Really


Google for Conway sequence, its one of the well known sequence and according to one paper (which is not freely available unfortunately) this sequence has many interesting properties.[/Color]

-- AI

Problem #1 is actually pretty simple. Below is a clue:

How many '1's are in line #1?

 

[Rahmuss]

Tenali, you solved the problem as it should have been written. You didn't read the way it was actually written closely enough.

"You have four people at a bridge... one HAS to carry a flashlight as they cross, but only two can cross at a time. And nobody can go alone."

As written, it pretty much makes the problem unsolvable unless you either have two flashlights or get to throw the only flashlight.

Actually, with this pointed out it seems that only one person has to carry the flashlight as they (singular person) cross. So you really only need one person to carry the flashlight as they cross. The others are free to go as they please. So let 10 and 5 start out, then after 5 minutes, let 2 go, then after 2 minutes let 1 go and finish walking with 10 (unless the name of 10 is "nobody"). Total time of 10 minutes.

 

[ArielGenesis]

1 3 1 1 2 2 2 1First 1 and 2 go across, then 1 comes back. Then 10 and 5 go across and then 2 comes back. Then 1 and 2 go across. Total time: 2 + 1 + 10 + 2 + 2 = 17.
]

"And nobody can go alone."
isn't 1 and 2 go alone when they say 'comes back'. Somehing like go back and threfore, go back alone.

 

[bhaichara]

Site for Microsoft Interview Questions

http://www.emicrosoftinterview.com -Guide for Microsoft Interview Questions

 

[michealsmith]

45 min ... burn both ropes at same time ..rope 1 from both ends and rope 2 from 1 end
wen rope 1 is burnout 30 min has gone ...and so out rope 2 which has 30 min left and then burn that from both ends instantaneouly affter rope 1 is ouit...even if its not instantaneous you would measure approxmatley 45 min plus 5 seconds or so

 

[arivero]

I am resusciting this problem in a new thread, https://www.physicsforums.com/forumdisplay.php?f=33 because it deserves more discussion. To begin, that the question with 45 mins needs two strings but the same question for 15 minutes needs only one string.

45 min ... burn

Spoiler

both ropes at same time ..rope 1 from both ends and rope 2 from 1 end
wen rope 1 is burnout 30 min has gone ...and so out rope 2 which has 30 min left and then burn that from both ends instantaneouly affter rope 1 is ouit...even if its not instantaneous you would measure approxmatley 45 min plus 5 seconds or so