Seeds within an nxn board
Source: Iberoamerican Olympiad 1990, Problem 5
May 21, 2007
analytic geometrycombinatorics proposedcombinatorics
Problem Statement
and are two opposite vertices of an board. Within each small square of the board, the diagonal parallel to is drawn, so that the board is divided in equal triangles. A coin moves from to along the grid, and for every segment of the grid that it visits, a seed is put in each triangle that contains the segment as a side. The path followed by the coin is such that no segment is visited more than once, and after the coins arrives at , there are exactly two seeds in each of the triangles of the board. Determine all the values of for which such scenario is possible.