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The New Coffee Room

  1. TNCR
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  3. Puzzle time - prisoners and hats

Puzzle time - prisoners and hats

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  • IvorythumperI Offline
    IvorythumperI Offline
    Ivorythumper
    wrote on last edited by
    #15

    If there are 25 colors, everyone can see ahead of themselves, and know what was said behind them, so they can know the color of their own hat.

    1 Reply Last reply
    • jon-nycJ Offline
      jon-nycJ Offline
      jon-nyc
      wrote on last edited by
      #16

      IT - there can be many people with the same color hat. Also by what method are you assuming the earlier people in line guessed their color correctly?

      Only non-witches get due process.

      • Cotton Mather, Salem Massachusetts, 1692
      IvorythumperI 1 Reply Last reply
      • jon-nycJ jon-nyc

        IT - there can be many people with the same color hat. Also by what method are you assuming the earlier people in line guessed their color correctly?

        IvorythumperI Offline
        IvorythumperI Offline
        Ivorythumper
        wrote on last edited by
        #17

        @jon-nyc said in Puzzle time - prisoners and hats:

        IT - there can be many people with the same color hat. Also by what method are you assuming the earlier people in line guessed their color correctly?

        "Twenty-five prisoners are given a list of colors ... each will be fitted with a hat whose color is on the list ... each prisoner in turn calls out a color from the list"

        "If there are 25 colors, everyone can see ahead of themselves... "

        Process of elimination -- this assumes the given list of colors corresponds to the actual hat colors, and there is only one hat per color -- which is implied by "each will be fitted with a hat whose color is on the list ".

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        • HoraceH Offline
          HoraceH Offline
          Horace
          wrote on last edited by
          #18

          Number of colors on the list was never specified in the original problem.

          Education is extremely important.

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          • LuFins DadL Offline
            LuFins DadL Offline
            LuFins Dad
            wrote on last edited by
            #19

            Are these male prisoners or female prisoners?

            8% of men are colorblind and .5% of women are.

            The Brad

            HoraceH George KG 2 Replies Last reply
            • LuFins DadL LuFins Dad

              Are these male prisoners or female prisoners?

              8% of men are colorblind and .5% of women are.

              HoraceH Offline
              HoraceH Offline
              Horace
              wrote on last edited by
              #20

              @lufins-dad said in Puzzle time - prisoners and hats:

              Are these male prisoners or female prisoners?

              8% of men are colorblind and .5% of women are.

              I doubt the puzzle creator even thought of this, due to our systemic visually impaired hatred. This is why those Microsoft people announce their appearance. I think we’ve all learned something from this puzzle - just not what the puzzle author intended.

              Let’s try to be kinder and more compassionate to the color blind moving forward.

              Education is extremely important.

              1 Reply Last reply
              • LuFins DadL LuFins Dad

                Are these male prisoners or female prisoners?

                8% of men are colorblind and .5% of women are.

                George KG Offline
                George KG Offline
                George K
                wrote on last edited by
                #21

                @lufins-dad said in Puzzle time - prisoners and hats:

                8% of men are colorblind and .5% of women are.

                Mens' eyes matter!

                "Now look here, you Baltic gas passer... " - Mik, 6/14/08

                The saying, "Lite is just one damn thing after another," is a gross understatement. The damn things overlap.

                1 Reply Last reply
                • jon-nycJ jon-nyc

                  For the two color case - black and white:

                  The last guy in line, who sees all hats except his own, calls out “black”, say, to communicate he can see an odd number of black hats. Otherwise, he says “white”, meaning he can see an even number of black hats.

                  He of course has only a chance of guessing his own color.

                  But the next guy will either see the same parity (odd/even) of black hats indicated in the first answer, or not. If he does, he can assume he has a white hat, if not he can assume black. Next in line same, after taking into account any ‘parity switch’ indicated by the second man’s stated color.

                  By that method all but the last in line (first guy to call his color) are freed.

                  Is there an analogous method for n colors?

                  jon-nycJ Offline
                  jon-nycJ Offline
                  jon-nyc
                  wrote on last edited by
                  #22

                  @jon-nyc said in Puzzle time - prisoners and hats:

                  For the two color case - black and white:

                  The last guy in line, who sees all hats except his own, calls out “black”, say, to communicate he can see an odd number of black hats. Otherwise, he says “white”, meaning he can see an even number of black hats.

                  He of course has only a chance of guessing his own color.

                  But the next guy will either see the same parity (odd/even) of black hats indicated in the first answer, or not. If he does, he can assume he has a white hat, if not he can assume black. Next in line same, after taking into account any ‘parity switch’ indicated by the second man’s stated color.

                  By that method all but the last in line (first guy to call his color) are freed.

                  Is there an analogous method for n colors?

                  Big hint: I can use slightly different words to describe this very same method and it will scale to n colors.

                  Only non-witches get due process.

                  • Cotton Mather, Salem Massachusetts, 1692
                  1 Reply Last reply
                  • KlausK Offline
                    KlausK Offline
                    Klaus
                    wrote on last edited by Klaus
                    #23

                    I guess the key operation is, as often in these kinds of puzzles, modulo n.

                    So everyone announces sum of colors (colors are numbered one to n) mod # of colors...

                    1 Reply Last reply
                    • jon-nycJ Offline
                      jon-nycJ Offline
                      jon-nyc
                      wrote on last edited by
                      #24

                      That’s exactly right.

                      Only non-witches get due process.

                      • Cotton Mather, Salem Massachusetts, 1692
                      KlausK 1 Reply Last reply
                      • jon-nycJ jon-nyc

                        That’s exactly right.

                        KlausK Offline
                        KlausK Offline
                        Klaus
                        wrote on last edited by
                        #25

                        Or, more precisely, only the first to announce does this and everybody else announces his own color.

                        1 Reply Last reply
                        • HoraceH Offline
                          HoraceH Offline
                          Horace
                          wrote on last edited by
                          #26

                          maga

                          Education is extremely important.

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