[刷题防痴呆] 0171 - Excel 表列序号 (Excel

题目地址

https://leetcode.com/problems/excel-sheet-column-number/description/

题目描述

171. 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
 

Constraints:

1 <= s.length <= 7
s consists only of uppercase English letters.
s is between "A" and "FXSHRXW".

思路

本质是26进制到10进制的转换.

关键点

注意, A对应的是1, 因此每一位sc[i] - 'A' + 1.

代码

• 语言支持：Java

class Solution {
    public int titleToNumber(String s) {
        char[] sc = s.toCharArray();
        int res = 0;
        for (int i = 0; i < sc.length; i++) {
            res = res * 26 + sc[i] - 'A' + 1;
        }
        
        return res;
    }
}