Enigma 1576: The holly and the ivy and the…
9 February 2012
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From New Scientist #2739, 19th December 2009 [link]
This year I have designed my own Christmas card. It consists of 16 squares pasted onto a card in a closely packed 4-by-4 array. There are four pictures of holly, four of ivy, four of mistletoe and four of fir trees. There are four background colours of gold, silver, red or white, and every combination of plant and background colour (such as holly on a red background) can be found.
In each row and in each column of the array there is one square of each plant and one square of each background colour. In the top row the colours (from left to right) are gold, silver, red and white.
The holly on a gold background touches the ivy on a silver background, whereas no two mistletoe squares are touching, not even at their corners. One row begins with a fir tree on a white background.
What (in order) are the other three squares in that row?