Some friends records in a text file (say, friends.json) -- one friend per line, JSON-encoded. I want to invite any friends within 100km of our New Delhi office (GPS coordinates 28.521134, 77.206567) for some food and drinks on us. Write a program that will read the full list of friends and output the names and user ids of matching friends (within 100km), sorted by user id (ascending).
Each friend's record will have the following attributes: id, name, latitude, longitude. Please use a test-case generating library (or just random number generators) to generate test data for the problem. Don't forget, latitudes lie in the range (-90,90) and longitudes (-180,180).