title: Minimum number of circles with radius r to cover n points
body: <p>What is the minimum number of circles with radius r needed to cover all n points?
  r and n will be given as input, followed by n pairs of integers representing the x-y co-ordinates of the n points.
  r is a real number and greater than 0. n is &lt; 20.</p>
  
  <p>A circle covers a point if the point lies inside the circle.
  A point lies inside a circle if the distance between the point and the center of the circle is less than or equal to r.</p>