# L-26 MCS 260 Fri 26 Oct 2007 : class Poly 

class Poly:
   "defines a polynomial in one variable"

   def __init__(self,c=0,p=0):
      "monomial with coefficient c and power p"
      if c==0:
         self.__L = []
      else:
         self.__L = [(c,p)]

   def addmon(self,c,p):
      "adds a monomial"
      if c != 0:
         done = False
         for i in range(0,len(self.__L)):
            m = self.__L[i]
            if m[1] == p:
               nc = c + m[0]
               del(self.__L[i])
               if nc != 0:
                  self.__L.append((nc,p))
               done = True
               break
         if not done:
            self.__L.append((c,p))

   def __add__(self,other):
      "adds two polynomials"
      p = Poly()
      for m in self.__L:
         p.addmon(m[0],m[1])
      for m in other.__L:
         p.addmon(m[0],m[1])
      return p

   def __str__(self):
      "returns a polynomial as a string"
      s = ''
      for m in self.__L:
         s += '%+2.f*x^%d' % (m[0],m[1])
      if s == '':
         return '0'
      else:
         return s