# L-13 MCS 275 Wed 10 Feb 2010 : treezoo.py

def Add(d):
   """
   Adds a new element to the dictionary,
   via interactive questions to the user.
   """
   if len(d) == 0:
      a = raw_input('What animal ? ')
      return [a]
   elif len(d) == 1:
      q = 'Is it \"' + d[0] + '\" ? (y/n) ' 
      a = raw_input(q)
      if a == 'y':
         print 'okay, got it'
         return d
      else:
         a = raw_input('What animal ? ')
         s = 'Give question to distinguish \"' + \
             a + '\" from \"' + d[0] + '\":\n'
         q = raw_input(s)
         return {'q':q,'y':[a],'n':[d[0]]}
   else:
      a = raw_input(d['q'] + ' (y/n) ')
      if a == 'y':
         return {'q':d['q'],'y':Add(d['y']),'n':d['n']}
      else:
         return {'q':d['q'],'y':d['y'],'n':Add(d['n'])}

def Navigate(d):
   """
   Navigates through the dictionary
   based on the user responses.
   """
   if len(d) == 1:
      print 'arrived at \"' + d[0] + '\"'
   elif len(d) == 3:
      a = raw_input(d['q'] + ' (y/n) ')
      Navigate(d[a])

def main():
   """
   Build interactively a tree to classify animals.
   """
   d = {}
   while True:
      d = Add(d)
      print 'd =', d
      a = raw_input("continue ? (y/n) ")
      if a != 'y': break
   print 'ended construction, start navigation...'
   while True:
      Navigate(d)
      a = raw_input("continue ? (y/n) ")
      if a != 'y': break

main()