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February 15, 2005 12:00 AM

The Logical Puzzle

SQL Server Pro
InstantDoc ID #44943

MARCH'S PUZZLE: TO A T
Draw the shapes that Figure A shows on a paper that has square gridlines, then cut the shapes out. Use the pieces to form a T shape with the proportions that Figure B shows. You might have to think outside the box for this one!

SOLUTION TO FEBRUARY'S CHOCOLATE PUZZLE
As a reminder, last month's puzzle asked you to calculate the minimum number of cuts required to break a 5-by-8 chocolate bar into its 40 individual pieces. You're allowed to cut only one piece at a time (but not to pile multiple pieces) and only in straight lines (horizontal or vertical).

Most people try to run several different scenarios, first cutting on each horizontal line, then cutting each row vertically, for example. It's confusing to run the different scenarios in your head, so you can easily make mistakes during your calculations and obtain different results for the various scenarios. The varying results you get by mistake can create the illusion that several options exist and that one method requires fewer cuts than another. But the truth is that, regardless of which method you use, you'll always end up making 39 cuts.

The proof uses induction. After no cuts, you have one piece. After one cut, you have two pieces. If you have n pieces and you cut one of them, you get n+1 pieces. In other words, the number of cuts required to get n pieces is n-1. Hence, the minimum—and only—number of cuts required to produce 40 pieces is 39.



ARTICLE TOOLS

Comments
  • DAN
    7 years ago
    Mar 26, 2005

    I think the instructions are intentionally vague about the requirements, and the solution is simple and only requires 3 of the peices. It doesn't say you have to use all the pieces, or that you can't over-lap them. Using all of them without over-lapping is the teasing part, because we are given the right amount of squares, but the shapes just don't fit.

    Using only the 3 bottom pieces (1x3, 2x2, 1x1):

    Rotate the L shaped piece so that it's 3 down, and two across, with one block acting as the right side of the cross-bar of the T.

    Rotate the the 2x2 block so that one square is the left side of the cross-bar of the T, and the
    other two squares overlap the top, center of the T, and the top square down the pillar.

    Now place the single square at the bottom of the pillar, and you have a T that looks like the solution, is 3 squares wide on top of a 3 square tall pillar, with a total height of 4 squares (though the total height is not necessarily essential)

    I'm surprised there aren't more responses. Did everyone just think this was too simple to write about?

  • Damir
    7 years ago
    Mar 03, 2005

    The desired shape is letter T which we can split into two rectangles (pillar and beam).
    We know that height of the pillar is the same as with of the beam. Height of the beam and width of the pillar can be different.

    The area of all puzzle pieces is 24. To create two rectangles with the same length (X) and combined area of 24 we have:

    1 - length 12
    [1x12] & [1x12]
    It is impossible to create two rectangles of height 1 as one (many) of given puzzle pieces are of height 2

    2 - length 8
    [1x8] & [2x8]
    [2x8] & [1x8]

    3 – length 6
    [1x6] & [3x6], [2x6] & [2x6], [3x6] & [1x6]
    It is impossible to create two rectangles of length 6 from given puzzle pieces.

    4 – length 4
    [1x4] & [5x4]
    [2x4] & [4x4]
    [3x4] & [3x4] ? doesn’t look like letter T, it is a rectangle
    [4x4] & [2x4] ? doesn’t look like letter T, it is a rectangle
    [5x4] & [1x4] ? doesn’t look like letter T, pillar is wider than the beam

    5 – length 3
    [4x3] & [4x3] ? doesn’t look like letter T, pillar is wider than the beam
    Other combinations for two rectangles of length 3 are impossible to create from given puzzle pieces.

    6 – length 1
    See solution 1


    I thing that with given puzzle pieces we can build desired shape using these combinations: [1x8] & [8x2], [2x8] & [8x1], [1x4] & [4x5], [2x4] & [4x4], [3x4] & [4x3]


    *First rectangle represents the pillar and second one represents the beam.
    ** First dimension represents width and second dimension represents height

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