problem 1:
describe, in detail, an algorithm which will draw a one-pixel wide outline of a circle of integer radius centered on the origin.
problem 2:
describe the modifications needed to your algorithm in part (1) to make it draw a filled circle.
problem 3:
describe the modifications needed to your algorithm in part (1) to make it draw the outline of a circle centered at arbitrary integer coordinates.
problem 4:
describe the modifications needed to your algorithm in part (3) to make it draw the outline of a circle centered at arbitrary non-integer coordinates and of non-integer radius.