171. Excel Sheet Column Number

Problem

Given a string columnTitle that represents the column title as appears in an Excel sheet, return its corresponding column number.

For example:

A -> 1
B -> 2
C -> 3
…
Z -> 26
AA -> 27
AB -> 28
…

https://leetcode.com/problems/excel-sheet-column-number/

Example 1:

Input: columnTitle = "A"
Output: 1

Example 2:

Input: columnTitle = "AB"
Output: 28

Example 3:

Input: columnTitle = "ZY"
Output: 701

Constraints:

• 1 <= columnTitle.length <= 7
• columnTitle consists only of uppercase English letters.
• columnTitle is in the range ["A", "FXSHRXW"].

Test Cases

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class Solution:
    def titleToNumber(self, columnTitle: str) -> int:

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import pytest

from solution import Solution


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

Thoughts

168. Excel Sheet Column Title 的反函数。

把每一个字母翻译成 1 到 26 的整数，乘以 26 的相应次幂即可。

168. Excel Sheet Column Title 代码中的 columnNumber - 1 对应于这里的 ord(c) - ord('A') + 1 = ord(c) - 64。

Code

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class Solution:
    def titleToNumber(self, columnTitle: str) -> int:
        num = 0
        for c in columnTitle:
            d = ord(c) - 64
            num = num * 26 + d

        return num

参考资料

• 本文引用

  • 168. Excel Sheet Column Title

许可协议

本文除了题目描述（Problem）部分之外，其他内容由 Calf 原创，采用 CC BY-NC-SA 4.0 许可协议，转载请注明出处。

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