---
title: 'LeetCode 171. Excel Sheet Column Number'
disqus: hackmd
---

# LeetCode 171. Excel Sheet Column Number

## Description

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
...

## Example

Input: columnTitle = "ZY"
Output: 701

## Constraints

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

## Answer

本題相當於進位轉換，將字元轉成26進位，所以每解一位數就將舊值*26+現值即可。

//2021_11_16
int titleToNumber(char * s) {
    int ans = 0;
    while(*s != '\0'){
        ans = ans * 26 + (*s - 'A' + 1);
        s++;
    }
    return ans;
}

## Link
https://leetcode.com/problems/excel-sheet-column-number/
###### tags: `Leetcode`