> For the complete documentation index, see [llms.txt](https://r24zeng.gitbook.io/leetcode-notebook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://r24zeng.gitbook.io/leetcode-notebook/bu-chong-4060-dao/168.-excel-sheet-column-title.md).

# 168. Excel Sheet Column Title

\# Easy

```python
class Solution:
    def convertToTitle(self, n: int) -> str:
        alp = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        return self.helper(n, alp)
    
    def helper(self, n, alp): 
        if n <= 26:
            return alp[n-1]     
        ch = alp[n%26-1]
        return self.helper(n//26, alp)+ch
```

该怎么计算时间复杂度呢？ $$O(log\_{26}^n)$$ --->  $$O(lgn)$$？ 空间复杂度也是一样的？