# 问题 原题链接：[https://leetcode.com/problems/excel-sheet-column-number/](https://leetcode.com/problems/excel-sheet-column-number/) Given a column title as appear in an Excel sheet, return its corresponding column number. For example: ``` A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28  ``` Example 1: ``` Input: "A" Output: 1 ``` Example 2: ``` Input: "AB" Output: 28 ``` Example 3: ``` Input: "ZY" Output: 701 ``` # 分析过程 - 输入：Excel 的行号 - 输出：十进制数 - 思路：本质为进制转换，26 进制转 10 进制 # 解决方法 ```cpp class Solution { public: int titleToNumber(string s) { size_t len = s.size(); int result = 0; for (int i = 0; i < len; i++) { char c = s[i]; if (c >= 'A' && c <= 'Z') { result = result * 26 + (c - 'A' + 1); } else { return 0; } } return result; } }; ```