[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 

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

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