Less fun, but more reliable possibly, is the mess-them-around-randomly-until-it-looks-right option.
It does this very stupidly, and will run indefinitely if you feed it something for which there is no solution. (If you're really unlucky it will run indefinitely if you feed it something really simple!)
- Peter
#!/usr/bin/env ruby
class Person
attr_reader :sname, :email
def initialize(details)
@fname, @sname, @email = details.scan(/(\w+)\s+(\w+)\s+<(.*)>/)[0]
end
def to_s() @fname + " " + @sname end
end
a, b = [], []
STDIN.each do |l|
someone = Person.new(l)
a << someone; b << someone
end
puts "Mixing..."
passes = 0
begin
ok = true
a.each_index do |idx|
passes += 1
if a[idx].sname == b[idx].sname
ok = false
r = rand(b.length); b[idx], b[r] = b[r], b[idx]
end
end
end until ok
a.each_index { |idx| puts "#{a[idx]} is santa'd with #{b[idx]}" }
puts "[#{passes} passes required.]"