beat/p-adic-numbers
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update poly.py

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Ata Deniz Aydin 2017-05-14 20:12:37 +03:00
parent 8851473c6e
commit b28a2e6438
1 changed files with 16 additions and 3 deletions
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19
poly.py
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@ -5,8 +5,8 @@ from collections import defaultdict
class Poly: class Poly:
'Polynomial class.' 'Polynomial class.'
def __init__(self, coeffs = None): def __init__(self, coeffs = None):
self.coeffs = defaultdict(int, not coeffs and {} or isinstance(coeffs, int) and {0:coeffs} or coeffs) self.coeffs = defaultdict(int, isinstance(coeffs, int) and {0:coeffs} or coeffs or {})
self.deg = int(self.coeffs and max(self.coeffs.keys())) self.deg = int(len(self.coeffs) and max(self.coeffs.keys()))
def __call__(self, val): def __call__(self, val):
'Evaluate polynomial for a given value.' 'Evaluate polynomial for a given value.'
@ -17,9 +17,13 @@ class Poly:
def __str__(self): def __str__(self):
def term(coeff, expt): def term(coeff, expt):
return ' * '.join(([] if coeff == 1 else [str(coeff)]) + ([] if expt == 0 else ['X'] if expt == 1 else ['X^' + expt])) if coeff == 1 and expt == 0:
return '1'
return ' * '.join(([] if coeff == 1 else [str(coeff)]) + ([] if expt == 0 else ['X'] if expt == 1 else ['X ** ' + expt]))
return ' + '.join(term(self.coeffs[i], i) for i in self.coeffs if self.coeffs[i] != 0) return ' + '.join(term(self.coeffs[i], i) for i in self.coeffs if self.coeffs[i] != 0)
def __repr__(self):
return str(self)
# arithmetic # arithmetic
def __add__(self, other): def __add__(self, other):
@ -56,6 +60,15 @@ class Poly:
if not isinstance(other, Poly): if not isinstance(other, Poly):
other = Poly(other) other = Poly(other)
return other.__mul__(self) return other.__mul__(self)
def __pow__(self, other):
if not isinstance(other, int) or other < 0:
raise ValueError("Exponent %d is not a natural number" % other)
res = Poly(1)
while other:
res *= self
other -= 1
return res
X = Poly({1:1}) X = Poly({1:1})