Add basic polynomial func and array to string func

nessesary/polynomial.py

@@ -1,6 +1,85 @@
-from parser.parser import polynomial_parse
+from parser.parser import parse_poly
 
 class Polynomial:
     def __init__(self, poly):
-        self.coeff = polynomial_parse(poly)
-        self.degree = len(polynomial_parse(poly)) - 1
+        if isinstance(poly, str):
+            self.coeff = parse_poly(poly)
+            self.degree = len(parse_poly(poly)) - 1
+            self.string_form = poly
+        elif isinstance(poly, list):
+            self.coeff = poly
+            self.degree = len(poly) - 1
+            self.string_form = self.to_str()
+        else:
+            raise ValueError
+
+    #[degree0, degree1, degree2]
+    def __add__(self, other):
+        """
+        >>> p1 = Polynomial([1, 1, 1, 1, 1])
+        >>> p2 = Polynomial([1, 1, 1, 1, 1])
+        >>> p3 = p1 + p2
+        >>> p3
+        2x^4+2x^3+2x^2+2x+2
+        """
+        if isinstance(other, Polynomial):
+            for degree_index in range(self.degree):
+                self.coeff[degree_index] += other.coeff[degree_index]
+        if isinstance(other, int) or isinstance(other, float):
+            pass
+
+
+    def __sub__(self, other):
+        """
+        >>> p1 = Polynomial([1, 1, 1, 1, 1])
+        >>> p2 = Polynomial([1, 1, 1, 1, 1])
+        >>> p3 = p1 - p2
+        >>> p3
+        0
+        """
+        if isinstance(other, Polynomial):
+            for degree_index in range(self.degree):
+                self.coeff[degree_index] -= other.coeff[degree_index]
+    
+    def __mul__(self, other):
+        if isinstance(other, Polynomial):
+            result = [0 for i in self.degree + other.degree]
+            for self_index in range(self.degree):
+                for other_index in range(other.degree):
+                    result[self_index+other_index] += self.coeff[self_index]*other.coeff[other_index]
+
+    def __pow__(self):
+        pass
+
+    def __truediv__(self):
+        pass
+
+    def to_str(self):
+        """
+        convert coefficient list into string.
+        >>> p1 = Polynomial([1, 1, 1, 1, 1])
+        >>> p1.to_str()
+        x^4+x^3+x^2+x+1
+        >>> p2 = Polynomial([-2, 4, 0, -1, 2])
+        >>> p2.to_str()
+        2x^4-x^3+4x-2
+        """
+        result = []
+        for ind in range(len(self.coeff)):
+            if self.coeff[ind]:
+                if ind == 0:
+                    temp = ""
+                elif ind == 1:
+                    temp = "x"
+                else:
+                    temp = "x^"+str(ind)
+                result.append(str(self.coeff[ind])+temp)
+
+        if result:
+            result.reverse()
+            return " + ".join(result)
+        else:
+            return "0"
+
+    def __str__(self) -> str:
+        return self.string_form