How can you plant seven straight rows of trees with six trees per row such that twenty-one trees are planted in total?

How can you plant nine straight rows of trees with three trees per row such that nine trees are planted in total?

Placed in an x,y plane my trees are located at:
(0,0) (0,1) (0,2) (1,1) (2,0) (2,1) (2,2) (4,0) and (4,2)

This only differs from Tristan's arrangement by the placement of the first tree in the second horizontal row.  This has the effect of the last trees in the first and third row being in 2 rows only while the first ones of these rows are members of 4 planting rows each; in Tristan's the end trees are each in 3 rows.


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I believe our combined efforts are therefore a full solution.

Posted by brianjn on 2006-10-23 03:44:58