Problem:
There is an ant which
can walk around on a planar grid. The ant can move one space at a time
left, right, up or down. That is, from (x, y) the ant can go to (x+1,
y), (x-1, y), (x, y+1), and (x, y-1). Points where the sum of the digits
of the x coordinate plus the sum of the digits of the y coordinate are
greater than 25 are inaccessible to the ant.
Example
For example, the point (59,
79) is inaccessible because 5 + 9 +...