How do I represent a hextile/hex grid in memory?

Question

Say I\'m building a board game with a hextile grid, like Settlers of Catan:

Note that

Answer 1

Such a grid can be represented in a two-dimensional array:

If

   2
7     3
   1   
6     4
   5

is the number one with its neighbors in the hex grid, then you can put this into a 2D array like so:

2 3
7 1 4
  6 5

Obviously neighbor-ness is determined in this grid not only by being horizontally or vertically adjacent but also using one diagonal.

You can use a graph too, if you like to, though.