You have 8 cards (pieces of paper) numbered from 1 to 8. The first 4 are all white, and the last 4 are all black. On each one is written:

#1: The next two cards are black.
#2: The next two cards are of different colors.
#3: The previous card has the same color as the next.
#4: There are the same number of black cards before and after this one.
#5: The previous card is of the same color as the next.
#6: The previous card is white.
#7: The next two cards are of the same color.
#8: The previous card is black.

Arrange the 8 cards in a row so that all the sentences result truthfully.

(In reply to re(2): No Subject by varadarajan)

The statement in the puzzle "The first 4 are all white, and the last 4 are all black." is taken to mean that cards 1 through 4 are white and cards 5 through 8 are the black ones. So card 2 should be white, for example.

In hindsight, perhaps the puzzle could have been clearer by specifying ace through 4 of hearts and 5 through 8 of clubs, and used hearts and clubs in the clues, but in any instance this restriction is what makes the solution unique.

Posted by Charlie on 2009-06-04 13:22:50