# More Puzzles

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 Very Difficult Logic Problems Coins on a Chessboard
 Tue Aug 30, 2016 4:48 am  by tartle A warden takes prisoner A into a room containing a chessboard, on each square of which is a coin randomly showing heads or tails. He then indicates a random square on that board. Prisoner A is given the chance to flip one coin (or none), then taken from the room, after which prisoner B is taken into the room and must say which square the warden indicated. The two prisoners may strategize beforehand, but may not communicate during the trial (except with the single coin flip). What should be their strategy?
 Sun Jan 08, 2017 3:23 am  by anon Does A turn the coin (A chooses) over or flip it by throwing it (random)?
 Sun Mar 26, 2017 9:48 pm  by batze Solution for a 2-square chessboard: HH -> HH / TH HT -> HH / HT TH -> HH / TH TT -> TT / HT The 2 cases are: 1. both the same 2. different And now a solution for a 3-square chessboard: HHH -> HHH / HTH / HHT HHT -> HHH / THT / HHT HTH -> HHH / HTH / TTH HTT -> TTT / HTH / HHT THH -> HHH / THT / THH THT -> TTT / THT / THH TTH -> TTT / HTH / THH TTT -> TTT / THT / TTH Here the 3 cases are: 1. all the same 2. single outlier in the middle 3. single outlier at the border This should be extendable to 64 squares, but the pattern rules will become more and more complicated.
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