added exam exercise 26

exam/ex26/main.py

@@ -0,0 +1,13 @@
+from polynomial import Polynomial
+
+p1 = Polynomial([0, 2, 3, 4, 0, 0, 9])
+p2 = Polynomial([0, 0, 1])
+p3 = Polynomial([1, 0, 0, 1])
+
+print("p1 = ", p1)
+print("p2 = ", p2)
+print("p3 = ", p3)
+
+print("p1  + p3 = ", p1 + p3)
+print("p2 * p3 = ", p2 * p3)
+print("p1 * p3 = ", p1 * p3)

exam/ex26/polynomial.py

@@ -0,0 +1,55 @@
+from collections import defaultdict
+
+class Polynomial(object):
+	__slots__ = ["koefficients"]
+
+	def __init__(self, koefficients):
+		self.koefficients = list(koefficients)
+		# Remove trailing zeros.
+		while(self.koefficients and self.koefficients[-1] == 0):
+			self.koefficients.pop()
+
+	def __call__(self, x):
+		if(not isinstance(x, (float, int, complex))):
+			raise TypeError("unsupported type for {}: {}".format(x, type(x)))
+
+		result = 0
+		for i, a in enumerate(self.koefficients):
+			result += a * x**i
+
+		return result
+
+	def __add__(self, other):
+		if(not isinstance(other, Polynomial)):
+			raise TypeError("cannot add {} and {}".format(type(self), type(other)))
+
+		p1 = self.koefficients
+		p2 = other.koefficients
+		if(len(other.koefficients) > len(self.koefficients)):
+			p1, p2 = p2, p1
+
+		p2 += [0] * (len(p1) - len(p2))
+
+		return Polynomial([a + b for a,b in zip(p1, p2)])
+
+	def __mul__(self, other):
+		if(isinstance(other, (int, float, complex))):
+			return Polynomial([a * other for a in self.koefficients])
+
+		if(not isinstance(other, Polynomial)):
+			raise TypeError("cannot add {} and {}".format(type(self), type(other)))
+
+		result = defaultdict(int)
+		for i, k1 in enumerate(self.koefficients):
+			for j, k2 in enumerate(other.koefficients):
+				result[i + j] += k1 * k2
+
+		
+		return Polynomial(result[i] for i in range(max(result)))
+
+	def __repr__(self):
+		return "{}({})".format(type(self).__name__, self.koefficients)
+	def __str__(self):
+		return " + ".join(["{}*x**{}".format(a, i) for i, a in enumerate(self.koefficients)])
+
+