merge sort for ikezawa-san

shuffle.rb

class Merge
  def initialize(*fnames)
    @file = fnames.collect {|fn| MergeFile.new(fn)}
    delete_empty
  end
  
  def delete_empty
    @file.delete_if {|f| f.empty?}
  end

  def empty?
    delete_empty
    @file.empty?
  end
  
  def pop
    @file.min.pop
  end
end

class Merge
  class MergeFile
    def initialize(fname)
      @file = File.open(fname)
      @curr = @file.gets
    end
    
    def empty?
      @curr.nil?
    end
    
    def peek
      @curr
    end
    
    def pop
      @curr
    ensure
      @curr = @file.gets
    end
    
    def <=>(other)
      peek <=> other.peek
    end
  end
end

if __FILE__ == $0
  merge = Merge.new(*ARGV)

  last = nil
  while ! merge.empty?
    curr = merge.pop
    next if last == curr
    last = curr
    puts curr
  end
end