URAL 1043 - Cover an Arc

First, find the center and the radius of the circle.
Since we are looking for a bounding rectangle, we need to calculate minX, maxX, minY, maxY.

Intuition: Just compare with the up-most, leftmost, rightmost and the down-most point of the circle!
Next, we have to determine whether a point on a circle is on an arc.

Arrange the two ends of the arc A,B such that A->B is clockwise.
To check whether P is on the arc, just see whether triangle APB is clockwise or not, which can be easily done by cross product.

Last Bug:

mnx = (int)(mnx+1e-10);
mny = (int)(mny+1e-10);
mxx = ceil(mxx-1e-10);
mxy = ceil(mxy-1e-10);

Correct version:

mnx = floor(mnx+1e-10);
mny = floor(mny+1e-10);
mxx = ceil(mxx-1e-10);
mxy = ceil(mxy-1e-10);

Incorrect version won't work with negative numbers..