Basic Calculator IV LeetCode solution in Python

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# Runtime: 62 ms (Top 83.61%) | Memory: 14.1 MB (Top 62.30%)
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class Term:
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    def __init__(
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        self, exp: Optional[str] = "", *, term: Optional[Mapping[str, int]] = {}
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    ) -> None:
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        self.d = defaultdict(int, **term)
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        if re.match(r"^\-?\d+$", exp):
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            self.d[""] += int(exp)
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        elif exp:
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            self.d[exp] += 1
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    def __add__(self, other: "Term") -> "Term":
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        return self._pm(other, add=True)
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    def __mul__(self, other: "Term") -> "Term":
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        res = defaultdict(int)
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        for (l_var, l_coef), (r_var, r_coef) in product(
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            self.d.items(), other.d.items()
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        ):
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            res["*".join(sorted(self._exp(l_var) + self._exp(r_var)))] += (
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                l_coef * r_coef
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            )
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        return Term(term=res)
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    def __sub__(self, other: "Term") -> "Term":
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        return self._pm(other, add=False)
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    def get(self) -> List[str]:
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        return [
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            str(coef) + "*" * bool(var) + var
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            for var, coef in sorted(
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                self.d.items(), key=lambda t: (-len(self._exp(t[0])), t[0])
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            )
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            if coef
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        ]
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    def _exp(self, var: str) -> List[str]:
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        return list(filter(bool, var.split("*")))
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    def _pm(self, other: "Term", *, add: bool) -> "Term":
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        res = copy.copy(self.d)
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        for var, coef in other.d.items():
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            res[var] += coef * (-1) ** (1 - add)
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        return Term(term=res)
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class Solution:
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    def basicCalculatorIV(
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        self, expression: str, evalvars: List[str], evalints: List[int]
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    ) -> List[str]:
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        vals = dict(zip(evalvars, evalints))
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        return eval(
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            re.sub(
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                r"[a-z0-9]+",
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                lambda m: "Term('" + str(vals.get(m.group(), m.group())) + "')",
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                expression,
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            )
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        ).get()