Excel Sheet Column Title — LeetCode 168 Python Solution

The problem

Given an integer columnNumber, return its corresponding column title as it appears in an Excel sheet. For example: A -> 1 B -> 2 C -> 3 ...

Example

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

Python solution

class Solution:
    def convertToTitle(self, columnNumber: int) -> str:
        res = []
        while columnNumber:
            columnNumber -= 1
            res.append(chr(ord('A') + columnNumber % 26))
            columnNumber //= 26
        return ''.join(res[::-1])

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 168. Excel Sheet Column Title is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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