Karatsuba Multiplication

Karatsuba.py

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+#x,y are strings
+def karatsuba(x,y):
+
+	len1 = len(x)
+	len2 = len(y)
+
+	if len1 <=10 or len2 <=10 :
+		return int(x)*int(y)
+
+	if len1 > len2:
+		y = y.rjust(len1,'0')
+		l = len1
+	else:
+		x = x.rjust(len2,'0')
+		l = len2
+
+	mid = l/2
+	x0 = x[:mid] 
+	x1 = x[mid:]
+	y0 = y[:mid]
+	y1 = y[mid:]
+
+	z0 = karatsuba(x0,y0)
+	z2 = karatsuba(x1,y1)
+	z1 = karatsuba(x0,y1)+karatsuba(x1,y0)
+
+	return ((10**l)*z0 + (10**((l)/2))*z1 + z2)