rankedVotingHelfer.rb

beginning = Time.now
def doRound (votePools, votes, round)
	votes.each do |voter|
		#check to see if the votepool contains the candidate
		voter.each do |vote|
			if votePools.has_key?(vote)
				votePools[vote].push(voter)
				break
			end
		end
	end
end

candidates = [:mark, :merrill, :neal, :troy, :alicia, :edmund, :bob, :jackie, :christopher, :dan, :james, :cyd]

#Generate some votes
perms = candidates.permutation(3).to_a
votes = 1000000.times.collect{ perms[ rand(perms.length) ] }
totalVotes = votes.length

#Store votes for each candidate in a hash of arrays
votePools = {}
candidates.each do |candidate| 
	votePools[candidate] = []
end

winner = false
round = 0

while winner != true do
	doRound votePools, votes, round
	sorted = votePools.sort_by{|k,v| -v.length};
	sorted.each do |x|
		print "#{x[0]}=#{x[1].length} "
	end
	print "\n"
	if(sorted.first[1].length.to_f / totalVotes.to_f > 0.5)
		puts "winner = candiate #{sorted.first[0]}"
		winner = true
	elsif (sorted.length == 1)
		puts "winner = candiate #{sorted.first[0]}"
		winner = true
	else
		votes = sorted.last[1]
		votePools.delete(sorted.last[0])
	end
end
puts "Time elapsed #{Time.now - beginning} seconds"

rankedVotingJoel.rb

beginning = Time.now
#make one ballot
names = [:mark, :merrill, :neal, :troy, :alicia, :edmund, :bob, :jackie, :christopher, :dan, :james, :cyd]

# find all permutations of the ballot
perms = names.permutation(3).to_a
pc =  perms.length
puts "#{pc} possible ballot permutations"

# get a bunch of random ballots
votes = 1000000.times.collect{ perms[ rand(pc) ] }


def is_anyone_majority(ballots)
	majority = ballots.count / 2
	counts = Hash.new(0)
	ballots.each{|x| counts[x[0]] += 1 } 
	biggest = counts.max_by{|x| x[1] }
	if biggest[1] > majority
		puts counts.inspect
		puts biggest[0]
	else
	   smallest = counts.min_by{|x| x[1] }
	   puts counts.inspect
		eliminate_last_place(ballots,smallest[0])
	end
end

def eliminate_last_place(all_ballots, last_place)
	is_anyone_majority( all_ballots.collect{|ranked_ballot| (ranked_ballot - [last_place]).delete_if{|x| x == [] } }.delete_if{|x| x == []} )
end

is_anyone_majority(votes)
puts "Time elapsed #{Time.now - beginning} seconds"