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52 changes: 52 additions & 0 deletions strings/integer_to_roman.py
Original file line number Diff line number Diff line change
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def integer_to_roman(number: int) -> str:
"""
Convert an integer to a Roman numeral.

Examples:
>>> integer_to_roman(1)
'I'
>>> integer_to_roman(4)
'IV'
>>> integer_to_roman(9)
'IX'
>>> integer_to_roman(58)
'LVIII'
>>> integer_to_roman(1994)
'MCMXCIV'
>>> integer_to_roman(0)
Traceback (most recent call last):
...
ValueError: number must be between 1 and 3999
"""
if not (1 <= number <= 3999):
raise ValueError("number must be between 1 and 3999")

symbols = [
(1000, "M"),
(900, "CM"),
(500, "D"),
(400, "CD"),
(100, "C"),
(90, "XC"),
(50, "L"),
(40, "XL"),
(10, "X"),
(9, "IX"),
(5, "V"),
(4, "IV"),
(1, "I"),
]

result = []
for value, numeral in symbols:
while number >= value:
result.append(numeral)
number -= value

return "".join(result)


if __name__ == "__main__":
import doctest

doctest.testmod()