Add class for Majority Judgment

mj.rb

@@ -0,0 +1,63 @@
+class MajorityJudgment
+
+  include Comparable
+  attr_reader :ratings, :count, :n, :majority
+
+  def initialize(arg)
+    if arg.is_a?(Array)
+      @ratings = arg
+      @count = { }
+      @n = 0
+      ratings.each do |r|
+        @count.has_key?(r) ? @count[r] = @count[r] + 1 : @count[r] = 1
+        @n = @n + 1
+      end
+    elsif arg.is_a?(Hash) 
+      @count = arg
+      @n = 0
+      @count.collect { |r, c| @n = @n + c }
+    end
+    @majority = ( @n.to_f / 2 ).floor + 1
+  end
+
+  def mj
+    s = 0
+    (1..6).to_a.reverse.each do |r|
+      s = s + @count[r] if @count[r]
+      return r if s >= @majority
+    end
+    return 0
+  end
+
+  def proponents(rating = self.mj)
+    p = 0
+    (rating+1..6).to_a.reverse.each do |r|
+      p = p + @count[r] if @count[r]
+    end
+    return p
+  end
+
+  def opponents(rating = self.mj)
+    o = 0
+    (1..rating-1).to_a.reverse.each do |r|
+      o = o + @count[r] if @count[r]
+    end
+    return o
+  end
+
+  def <=> (other)
+    return 1 if self.mj > other.mj
+    return -1 if self.mj < other.mj
+    return 0 if self.mj == 0
+    counta = self.count.dup
+    counta[self.mj] = counta[self.mj] - 1
+    countb = other.count.dup
+    countb[other.mj] = countb[other.mj] - 1
+    return MajorityJudgment.new(counta) <=> MajorityJudgment.new(countb)
+  end
+
+  def to_s
+    puts "#{@count}: {M=>#{self.mj}, P=>#{self.proponents}, O=>#{self.opponents}}"
+  end
+
+end