sawine@3: """
sawine@3: Name: string_hash -  a string hashing program
sawine@3: Description: Basic string hashing program according to Theory I lecture.
sawine@3: Author: Eugen Sawin <sawine@informatik.uni-freiburg.de>
sawine@3: """
sawine@3: 
sawine@3: def main():    
sawine@3:     args = parse_arguments()
sawine@3:     used = set()
sawine@3:     for key in args.values.split():
sawine@3:         print "%s: %i" % (key, double_hash(int(key), used))
sawine@3: 
sawine@3: def double_hash(k, used):
sawine@3:     j = 0
sawine@3:     code = (h(k) - s(j, k)) % 15
sawine@3:     while code in used:
sawine@3:         j += 1
sawine@3:         code = (h(k) - s(j, k)) % 15
sawine@3:     used.add(code)
sawine@3:     return code
sawine@3: 
sawine@3: def s(j, k):
sawine@3:     return j * h2(k)
sawine@3: 
sawine@3: def h(k):
sawine@3:     return k % 15
sawine@3: 
sawine@3: def h2(k):
sawine@3:     return 1 + (k % 13) 
sawine@3: 
sawine@3: from argparse import ArgumentParser
sawine@3: 
sawine@3: def parse_arguments():
sawine@3:     parser = ArgumentParser(description="Returns the hash for given string using the double-hash technique.")
sawine@3:     parser.add_argument("values", help="values")    
sawine@3:     return parser.parse_args()
sawine@3: 
sawine@3: if __name__ == "__main__":
sawine@3:     main()