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Yellow,Green,Red,Blue


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#1 wolfgang

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Posted 13 January 2013 - 10:40 AM

An unknown number of prisoners( more than 14)were told a day before their execution, that they are going to be blind folded, and a colored paper(either.. yellow,green,red or blue) will be  glued on forehead of each one of them( no one can see his own paper), then they should inter a big hall one by one to make 4 raws in this order( Yellow,Green,Red,Blue)i.e. a raw of Yallows, a raw of Greens  etc.,each one will be unfolded when he inters the hall.No one of them is allowed to arrenge the others,each one should himslf choose where to stay, once he did,he can not change his place( only the first 2 prisoners can change their minds only once).Any kind of comunication between them is not allowed. If any one of them stands in a wrong raw, all of them will die!

All colores were used.

They should make a plane which saves all of them, can you help them?


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#2 Rainman

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Posted 13 January 2013 - 01:46 PM

Spoiler for solution


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#3 plasmid

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Posted 13 January 2013 - 08:55 PM

Spoiler for solution

I think the problem's set up in such a way that you can't use that strategy. The people are blindfolded until they enter the room. So the first person won't see anyone's color, the second person will only see the first person's color, etc.

Just for clarification, are there set positions where each row should form? In other words, should we treat this as if there are four rows of seats and all of the yellows must sit in the first row and all the greens in the second row etc.? Or instead can they form rows wherever they want, so if the first person to enter is yellow he can he stand anywhere in the room as long as all the other colors stand somewhere behind him?
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#4 Pankaj Varma

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Posted 14 January 2013 - 06:38 AM

The suggested solution assumes that their are equal number of each color slip and the each person, when he enters can see every other forehead and count the color papers glued there. We need a more innovative solution, I guess.


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#5 Prime

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Posted 14 January 2013 - 06:45 AM

I don't see the OP requiring each prisoner to assume his position before the next one enters the room. So why should we be adding such a restriction?

On the other hand, the OP never specified that the place for each row has been marked with like colored chairs, tile, or in any other way. Thus we must not assume that it has.

Given the above, Rainman's method needs just a slight modification.

Spoiler for how about

As for the blindfold, it is kept on until each captive enters the hall to prevent them from seeing the color when it is placed upon their heads and thereafter to hinder them from checking the same in the mirror of the dressing room.

 

 


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Past prime, actually.


#6 TimeSpaceLightForce

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Posted 14 January 2013 - 01:28 PM

Spoiler for


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#7 wolfgang

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Posted 14 January 2013 - 10:28 PM

 

Spoiler for solution

I think the problem's set up in such a way that you can't use that strategy. The people are blindfolded until they enter the room. So the first person won't see anyone's color, the second person will only see the first person's color, etc.

Just for clarification, are there set positions where each row should form? In other words, should we treat this as if there are four rows of seats and all of the yellows must sit in the first row and all the greens in the second row etc.? Or instead can they form rows wherever they want, so if the first person to enter is yellow he can he stand anywhere in the room as long as all the other colors stand somewhere behind him?

 

They can form raws whenever they want


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#8 wolfgang

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Posted 14 January 2013 - 10:30 PM

The suggested solution assumes that their are equal number of each color slip and the each person, when he enters can see every other forehead and count the color papers glued there. We need a more innovative solution, I guess.

The colors are not equal


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#9 wolfgang

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Posted 14 January 2013 - 10:41 PM

Spoiler for

I said in the OP",each one should himslf choose where to stay, once he did,he can not change his place".and with this method each one stays infront  of 1 making a raw,so can not change his place.


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#10 bonanova

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Posted 15 January 2013 - 01:08 AM

This is a challenge.
A two-color version requires and permits movement after taking one's position.
So I don't think it provides useful guidance for this case

Spoiler for here it is anyway

Great puzzle.
Eager to see the solution.
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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell




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