Homework11

class Equation:
    def __init__(self, terms, coeffs):
        self.terms = terms
        self.coeffs = coeffs
    def __str__(self):
        result = ''
        for i in range(0, len(self.terms)):
            if self.coeffs[i] > 0:
                if i == 0:
                    result = result + str(self.coeffs[i]) 
                else:
                    result = result + ' + ' + str(self.coeffs[i]) 
            elif self.coeffs[i] < 0:
                result = result + ' - ' + str(abs(self.coeffs[i])) 
            result = result + self.terms[i]
        return result
    def multiply(self, eqn):
        rterms = []
        for t1 in self.terms:
            t1 = self.unbox(t1)
            for t2 in eqn.terms:                
                t2 = self.unbox(t2)
                t = t1 + t2
                t = ''.join(sorted(t))
                t = self.box(t)
                rterms.append(t)
        rcoeffs = []
        for c1 in self.coeffs:
            for c2 in eqn.coeffs:
                c = c1 * c2
                rcoeffs.append(c)
        result = Equation(rterms, rcoeffs)
        return result
    def coeff(self, term):
        result = 0
        for t in range(0, len(self.terms)):
            if self.terms[t] == term:
                result = result + int(self.coeffs[t])
        return result
    def box(self, term):
        result = ''
        count = 0
        char = ''
        for i in range(0, len(term)):
            if char == term[i]:
                count = count + 1
            else:
                if char != '':
                    result = result + char + '^' + str(count)
                count = 1
                char = term[i]
        if char != '':
            result = result + char + '^' + str(count)
        return result
    def unbox(self, term):
        result = ''
        for t in range(0,len(term),3):
            variable = term[t]
            power = int(term[t+2])
            for p in range(0,power):
                result = result + variable
        return result

e = Equation(['a^1', 'b^1', 'c^1'], [1, 2, 3]) #(a + 2b + 3c)
r = Equation([''], [1]) # identity
for i in range(0,6):
    r = r.multiply(e)
print r
print r.coeff("a^1b^2c^3")