Leetcode: 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 

 1 public class Solution {
 2     public int titleToNumber(String s) {
 3         int res = 0;
 4         for (int i=0; i<s.length(); i++) {
 5             char c = s.charAt(i);
 6             res += (int)(c - ‘A‘ + 1) * Math.pow(26, s.length()-i-1);
 7         }
 8         return res;
 9     }
10 }