168. Excel Sheet Column Title

import pytest

from solution import Solution


@pytest.mark.parametrize('columnNumber, expected', [
    (1, "A"),
    (28, "AB"),
    (701, "ZY"),
])
@pytest.mark.parametrize('sol', [Solution()])
def test_solution(sol, columnNumber, expected):
    assert sol.convertToTitle(columnNumber) == expected

from string import ascii_uppercase


class Solution:
    def convertToTitle(self, columnNumber: int) -> str:
        parts = []
        while columnNumber > 0:
            columnNumber, remain = divmod(columnNumber - 1, 26)
            parts.append(ascii_uppercase[remain])

        parts.reverse()
        return ''.join(parts)