"""

 Name: string_hash -  a string hashing program

 Description: Basic string hashing program according to Theory I lecture.

 Author: Eugen Sawin <sawine@informatik.uni-freiburg.de>

 """

 def main():    

     args = parse_arguments()

     used = set()

     for key in args.values.split():

         print "%s: %i" % (key, double_hash(int(key), used))

 def double_hash(k, used):

     j = 0

     code = (h(k) - s(j, k)) % 15

     while code in used:

         j += 1

         code = (h(k) - s(j, k)) % 15

     used.add(code)

     return code

 def s(j, k):

     return j * h2(k)

 def h(k):

     return k % 15

 def h2(k):

     return 1 + (k % 13) 

 from argparse import ArgumentParser

 def parse_arguments():

     parser = ArgumentParser(description="Returns the hash for given string using the double-hash technique.")

     parser.add_argument("values", help="values")    

     return parser.parse_args()

 if __name__ == "__main__":

     main()