Suppose I have a circle intersecting a rectangle, what is ideally the least cpu intensive way between the two?

1. method A

   1. calculate rectangle boundaries
   2. loop through all points of the circle and, for each of those, check if inside the rect.

2. method B

   1. calculate rectangle boundaries
   2. check where the center of the circle is, compared to the rectangle

   3. make 9 switch/case statements for the following positions:

      • top, bottom, left, right
      • top left, top right, bottom left, bottom right
      • inside rectangle

   4. check only one distance using the circle's radius depending on where the circle happens t be.

I know there are other ways that are definitely better than these two, and if could point me a link to them, would be great but, exactly between those two, which one would you consider to be better, regarding both performance and quality/precision?

Thanks in advance.