string_extension.rb

二叉树详细源码

class String
  # If length is greater than the self.lenth, returns a new String, it's length equals to +length+,
  # content is distributed center, padded with +padstr+; otherwise, returns self.
  # Example
  #    - "ab".distribute_center(1,'.')     #=> "ab"
  #    - "ab".distribute_center(2,'.')     #=> "ab"
  #    - "ab".distribute_center(3,'.')     #=> "ab."
  #    - "ab".distribute_center(4,'.')     #=> ".a.b"
  #    - "ab".distribute_center(5,'.')     #=> ".a.b."
  #    - "ab".distribute_center(6,'.')     #=> ".a.b.."
  #    - "ab".distribute_center(7,'.')     #=> "..a..b."
  #    - "ab".distribute_center(8,'.')     #=> "..a..b.."
  #    - "ab".distribute_center(9,'.')     #=> "..a..b..."
  #    - "ab".distribute_center(10,'.')    #=> "...a...b.."
  #    - "ab".distribute_center(11,'.')    #=> "...a...b..."
  def distribute_center(length, padstr=' ')
    return self if length <= self.length
    
    # e.g "ab".distribute_center(10)
    spaces_count_toadd = length - self.length  # will be 10-2=8 <-> "123a456b78"
    points_count_toinserted = self.length+1 # will be 2+1 = 3 <-> "1a2b3"
    space_count_everypoint_toadd = (spaces_count_toadd*1.0/points_count_toinserted).round
    
    result = ""
    
    (0..self.length-1).each do |i|
      result << "".center(space_count_everypoint_toadd, padstr) + self[i,1]    
    end
    
    return result.ljust(length, padstr)
  end
end