Given $n$ circles all with radius $r$ and one point on a 2D plane, what is the best algorithm to find all circles that contain the given point. The circles and the point can change their positions.
The simple approach would be to iterate through each circle and then apply the good old circle equation, that is: check whether the distance between the center of the circle and the point is less than the radius of the circle. One query would be of complexity $O(n)$. Is there a faster algorithm?