So I was at a bbq with a bunch of other tech friends and the discussion turned to programming job interview questions.
The question was could you move a robot in a circle, given only the circumference, and tell when the robot left the circle.
This repro solves that problem.
This uses python 3 with pygame (for graphics)
Set the circle initial x,y center coordinates and the circle circumference.
#The circle
circlecenterx=-3
circlecentery=4
circumference=(10 * math.pi)
radius=circumference / (2 * math.pi)
Do not change the radius formula
The robot starts at the center of the circle
#The robot
robotx=circlecenterx
roboty=circlecentery
Once you start the app, you can go the pygame screen and move the robot around with the arrow keys. q = quit