87 lines
2.2 KiB
Python
87 lines
2.2 KiB
Python
# https://www.codewars.com/kata/55f89832ac9a66518f000118/
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import re
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from dataclasses import dataclass
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@dataclass
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class Term:
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coef: int
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variables: str
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def __repr__(self):
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return f"Term(coef={self.coef}, vars={self.variables})"
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def __str__(self):
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a = str(self.coef) if self.coef != 1 else ""
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a = "-" if a == "-1" else a
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b = "".join(self.variables)
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return f"{a}{b}"
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def __add__(self, other):
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if self.variables == other.variables:
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r = Term(self.coef + other.coef, self.variables)
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return r
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raise ArithmeticError("Variables do not match")
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def __lt__(self, other):
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if len(self.variables) == len(other.variables):
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return self.variables < other.variables
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return len(self.variables) < len(other.variables)
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def __eq__(self, other):
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return self.coef == other.coef and self.variables == other.variables
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def parse_term(inp: str) -> Term:
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sign, coef, variables = "", [], []
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for n in inp:
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if n == "-":
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sign = "-"
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elif n.isnumeric():
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coef.append(n)
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elif n.isalpha():
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variables.append(n)
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c = -1 if sign == "-" else 1
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c *= int("".join(coef)) if coef else 1
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return Term(c, sorted(variables))
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def simplify_terms(terms: [Term]) -> [Term]:
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simplified_terms = []
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for term in terms:
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if not simplified_terms:
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simplified_terms.append(term)
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continue
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previous = simplified_terms.pop()
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try:
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res = previous + term
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if res.coef != 0:
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simplified_terms.append(res)
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except ArithmeticError: # terms not compatible to be added
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simplified_terms.append(previous)
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simplified_terms.append(term)
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return simplified_terms
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def poly_to_str(terms: [Term]) -> str:
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res = ""
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for term in terms:
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s = str(term)
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if res and not s.startswith("-"):
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res += "+"
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res += s
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else:
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res += s
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return res
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def simplify(poly: str):
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pattern = r"([+-]?\d*\w+)"
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terms = sorted(parse_term(t) for t in re.findall(pattern, poly))
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simplified_terms = simplify_terms(terms)
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return poly_to_str(simplified_terms)
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