58 lines
1.1 KiB
Python
58 lines
1.1 KiB
Python
SIMPLE = {
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"I": 1,
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"V": 5,
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"X": 10,
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"L": 50,
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"C": 100,
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"D": 500,
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"M": 1000,
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}
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SIMPLE_REVERSE = {v: k for k, v in SIMPLE.items()}
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COMPOUND = {
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"IV": 4,
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"IX": 9,
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"XL": 40,
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"XC": 90,
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"CD": 400,
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"CM": 900,
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}
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PREFIXES = {k[0] for k in COMPOUND.keys()}
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COMPOUND_REVERSE = {v: k for k, v in COMPOUND.items()}
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ALL = SIMPLE | COMPOUND
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ALL_REVERSE = {v: k for k, v in ALL.items()}
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def i2r(i: int) -> str:
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if i > 100_000:
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raise ValueError(f"{i} is too silly")
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r: list[str] = []
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for int_val, roman_val in sorted(ALL_REVERSE.items(), reverse=True):
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remainder = i % int_val
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r += [roman_val] * int((i - remainder) / int_val)
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i = remainder
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return "".join(r)
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def r2i(r: str) -> int:
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total = 0
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offset = 0
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for i in range(len(r)):
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if i + offset > len(r) - 1:
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break
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c = r[i + offset]
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if c in PREFIXES and (i + offset + 1) < len(r) and c + r[i + offset + 1] in ALL:
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total += ALL[c + r[i + offset + 1]]
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offset += 1
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continue
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total += ALL[c]
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return total
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