Code that generates the population distribution map for a specified country and outputs it as an image:
GeoGraphics[{CountryData["Romania"],Opacity[0.042, Red],Disk[Reverse[CityData[#, "Coordinates"]],Log[10.^18, QuantityMagnitude[CityData[#, "Population"]]]] & /@ CityData[{All, "Romania"}]}]
The sample is written with Wolfram Language, a very powerful symbolic language with built-in algorithms and knowledge base.