# LeetCode 168. Excel Sheet Column Title

## Description

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

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"
```

Example 4:

```Input: columnNumber = 2147483647
Output: "FXSHRXW"
```

Constraints:

• `1 <= columnNumber <= 231 - 1`

## Explanation

Every 26 number repeats letter ‘A’ and base on the relationship with 26 to find the letter.

## Python Solution

``````class Solution:
def convertToTitle(self, columnNumber: int) -> str:

result = ""

while columnNumber > 0:
result = chr(ord('A') + (columnNumber - 1) % 26) + result
columnNumber = (columnNumber - 1) // 26

return result
``````
• Time Complexity: O(N).
• Space Complexity: O(N).