Pairing Algorithm

pairings.rb

require 'pp'
devs = %w{ Andrew Anthony Ben Matt Tom Zac }
devs << nil if devs.length.odd? 
 
top, bottom = devs.each_slice(devs.length/2).to_a
pivot, *top = top
 
result = []
(devs.length-1).times do
  top.unshift(bottom.shift)
  bottom.push(top.pop)
  result << [pivot,*top].zip(bottom)
end
 
pp result
 
# [[["Andrew", "Tom"], ["Matt", "Zac"], ["Anthony", "Ben"]],
#  [["Andrew", "Zac"], ["Tom", "Ben"], ["Matt", "Anthony"]],
#  [["Andrew", "Ben"], ["Zac", "Anthony"], ["Tom", "Matt"]],
#  [["Andrew", "Anthony"], ["Ben", "Matt"], ["Zac", "Tom"]],
#  [["Andrew", "Matt"], ["Anthony", "Tom"], ["Ben", "Zac"]]]
 
# ********************************************************************
 
# Smaller less readable version
require 'pp'
devs = %w{ Andrew Anthony Ben Matt Tom Zac }
devs << nil if devs.length.odd?
 
pivot, *rest = devs
 
result = []
(rest.length).times do
  bottom, top = rest.rotate!.each_slice(devs.length / 2).to_a
  result << [pivot,*top].zip(bottom.reverse)
end
 
pp result
 
# [[["Andrew", "Tom"], ["Zac", "Matt"], ["Anthony", "Ben"]],
#  [["Andrew", "Zac"], ["Anthony", "Tom"], ["Ben", "Matt"]],
#  [["Andrew", "Anthony"], ["Ben", "Zac"], ["Matt", "Tom"]],
#  [["Andrew", "Ben"], ["Matt", "Anthony"], ["Tom", "Zac"]],
#  [["Andrew", "Matt"], ["Tom", "Ben"], ["Zac", "Anthony"]]]
 
# ********************************************************************
 
# Here is an approach without manipulating existing arrays
# That uses math instead of Queues. This would be the memory
# optimized version.
 
require 'pp'
devs = %w{ Andrew Anthony Ben Matt Tom Zac }
 
index = Array.new devs.length
 
i = 0
x = 1
while i < devs.length
  index[i] = x - 1
  index[i+1] = devs.length - x
  i += 2
  x += 1
end
 
result = Array.new(devs.length - 1) { Array.new(devs.length/2) }
result.each do |row|
  i = j = 0
  while j < devs.length
    row[i] = [ devs[index[j]], devs[index[j+1]] ]
    i += 1
    j += 2
  end
 
  (devs.length - 1).times do |i|
    index[i+1] = (index[i+1] + 1) % (devs.length - 1) + 1
  end
end
 
pp result
 
# [[["Andrew", "Zac"], ["Anthony", "Tom"], ["Ben", "Matt"]],
#  [["Andrew", "Ben"], ["Matt", "Anthony"], ["Tom", "Zac"]],
#  [["Andrew", "Tom"], ["Zac", "Matt"], ["Anthony", "Ben"]],
#  [["Andrew", "Anthony"], ["Ben", "Zac"], ["Matt", "Tom"]],
#  [["Andrew", "Matt"], ["Tom", "Ben"], ["Zac", "Anthony"]]]

I'm having way tooooooo much fun with this.