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how to implement a short url like urls in twitter?
12341235.to_s(36)
#=> "7cik3"

"7cik3".to_i(36)
#=> 12341235

module AnyBase
  ENCODER = Hash.new do |h,k|
    h[k] = Hash[ k.chars.map.with_index.to_a.map(&:reverse) ]
  end
  DECODER = Hash.new do |h,k|
    h[k] = Hash[ k.chars.map.with_index.to_a ]
  end
  def self.encode( value, keys )
    ring = ENCODER[keys]
    base = keys.length
    result = []
    until value == 0
      result << ring[ value % base ]
      value /= base
    end
    result.reverse.join
  end
  def self.decode( string, keys )
    ring = DECODER[keys]
    base = keys.length
    string.reverse.chars.with_index.inject(0) do |sum,(char,i)|
      sum + ring[char] * base**i
    end
  end
end

base36 = "0123456789abcdefghijklmnopqrstuvwxyz"
db_id = 12341235
p AnyBase.encode( db_id, base36 )
#=> "7cik3"
p AnyBase.decode( "7cik3", base36 )
#=> 12341235

base62 = [ *0..9, *'a'..'z', *'A'..'Z' ].join
p AnyBase.encode( db_id, base62 )
#=> "PMwb"
p AnyBase.decode( "PMwb", base62 )
#=> 12341235

gem install bitly

# Use api version 3 or get a deprecation warning
Bitly.use_api_version_3

# Create a client
bitly = Bitly.new(username, api_key)

# Call method shorten
bitly.shorten('http://www.google.com').short_url