Best position for contour placement
<p>I have a graph where the nodes represent cities (City object has population and coordinates as fields) and the edges represent the distance between them. How to calculate the center of a circular contour, so that it covers the most population (not node count!)? 
1)The graph is used to represent infrastructural state, which is irrelevant for the question at hand.
2)The circle itself is constrained by size (radius). Basically, I'm trying to simulate a nuclear hit.</p>

<p>Is there an out of the box algorithm  for this?</p>