168. Excel Sheet Column Title

Easy

---

Given an integer columnNumber, return its corresponding column title as it appears in an Excel sheet.

For example:

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

Example 1:

Input: columnNumber = 1
Output: "A"

Example 2:

Input: columnNumber = 28
Output: "AB"

Example 3:

Input: columnNumber = 701
Output: "ZY"

Constraints:

• 1 <= columnNumber <= 231 - 1

class Solution:
    def convertToTitle(self, columnNumber: int) -> str:
        if columnNumber == 0:
            return ""
        else:
            # Why -1 here , think using 'A' character it will be clear
            return self.convertToTitle((columnNumber-1)//26) + chr((columnNumber-1) % 26 + ord('A'))