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The New Coffee Room

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  3. Puzzle time - prisoners and hats

Puzzle time - prisoners and hats

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  • 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 ".

      1 Reply Last reply
      • 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.

        1 Reply Last reply
        • 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.

                        1 Reply Last reply
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