"""

Integer to Roman Numeral

Given an integer, convert it to a Roman numeral string. Input is guaranteed

to be within the range from 1 to 3999.

Reference: https://en.wikipedia.org/wiki/Roman_numerals

Complexity:

Time: O(1) since the input range is bounded

Space: O(1)

"""

from __future__ import annotations

def int_to_roman(num: int) -> str:

"""Convert an integer to its Roman numeral representation.

Args:

num: An integer between 1 and 3999.

Returns:

The Roman numeral string for the given integer.

Examples:

>>> int_to_roman(644)

'DCXLIV'

"""

thousands = ["", "M", "MM", "MMM"]

hundreds = ["", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"]

tens = ["", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"]

ones = ["", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"]

return (

thousands[num // 1000]

+ hundreds[(num % 1000) // 100]

+ tens[(num % 100) // 10]

+ ones[num % 10]

)