santa.dart A try to learn dart, solution to the "santa problem" https://plus.google.com/118397406534237711570/posts/XjgFRvqtVA4

santa.dart

import 'dart:io';
import 'dart:async';
import 'dart:convert';
import 'dart:collection';

void main() {
  print("Please, enter 'first name' and 'last name' finish with a empty line\n");
  Stream cmdLine = stdin
      .transform(UTF8.decoder)
      .transform(new LineSplitter());
     
  List<Person> persons = [];
  List<SantaPair> santaPairs = [];
  
  cmdLine.listen((data) {
    switch(data) {
      case '':
        createSantaPairs(persons, santaPairs);
        print(santaPairs);
        exit(1);
        break;
      default:
        addPerson(persons, data);
    }
  });
 
}

createSantaPairs(List<Person> persons, List<SantaPair> santaPairs) {
  persons.sort((e1, e2) => e1.lastName.compareTo(e2.lastName));
  Queue q = new Queue.from(persons);
  while (q.isNotEmpty && q.length >= 2) {
    var first = q.removeFirst();
    var last = q.removeLast();
    if (first.lastName == last.lastName) {
      print("No combination possible");
      exit(0);
    }
    santaPairs.add(new SantaPair(first, last));
  }
}

addPerson(List<Person> persons, String data) {
  var fullName = data.split(' ');
  persons.add(new Person(fullName[0], fullName[1]));
}
class SantaPair {
  var person1;
  var person2;
  SantaPair(this.person1, this.person2);
  toString() => "(${person1}, ${person2})";
}

class Person {
  var firstName;
  var lastName;
  Person(this.firstName, this.lastName);  
  toString() => "${firstName} ${lastName}";
}