excel Sheet Column Number

Related to question Excel Sheet Column Title

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 

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

public class Solution {

    public int titleToNumber(String s) {        

    }

}

该题和

Excel Sheet Column Title

 对应，不过是反过来了，给你一个excel列的名字，返回起列数。

    public static int titleToNumber(String s) {    if(s==null) return 0;    int result=0;        for(int i=s.length()-1;i>=0;i--){        result +=Math.pow(26, s.length()-1-i)*(s.charAt(i)-'A'+1);        }        return result;    }