We have a collection of possibly overlapping 45 degree isosceles right triangles.
Each triangle is oriented with its hypotenuse at the bottom, parallel with the
x axis. Each triangle is specified by giving the center point (xCenter,yCenter)
of its hypotenuse and the height. For example, a triangle with center at (1,3) and with height 7
would have its three vertices at (6,3), (8,3), and (1,10).
We need to know the area that is covered by the collection of triangles. Of
course, we don't want to count overlapping areas multiple times. Create a
class TriArea that contains a method area that is given int[]s xCenter, yCenter,
and height and returns the area covered. The specification of the ith
triangle is given by the ith element of xCenter,
yCenter, and height.
