CityFinder.linq

<Query Kind="Statements">
  <NuGetReference>CsvHelper</NuGetReference>
  <Namespace>CsvHelper</Namespace>
</Query>

// NPR Sunday Puzzle for 2017-12-24

// city data: https://github.com/grammakov/USA-cities-and-states

var cities = new List<string>();
var config = new CsvHelper.Configuration.Configuration{Delimiter = "|", HasHeaderRecord = true};
var tr = File.OpenText(@"C:\temp\cities\USA-cities-and-states-master\us_cities_states_counties.csv");
var reader = new CsvHelper.CsvReader(tr, config);

reader.Read();
while (reader.Read())
{
	var city = reader[0];
	if (!cities.Contains(city))
	{
		cities.Add(city);
	}
}

cities
	.Select (
		city => 
		{
			return city.Replace(" ", "").Replace(".", "").ToLower();
		})
	.Cast<IEnumerable<char>>()
	.Where (
		city => city.Count() == 10 && city.Distinct().Count() == 3
		).Dump();