Related to questionExcel 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@tsfor adding this problem and creating all test cases.

class Solution {
    public int titleToNumber(String s) {

        int ans = 0;
        for (int i = 0; i < s.length(); i++){
            int num = s.charAt(i) - 'A';
            num++;

            ans = ans * 26 + num;
        }

        return ans;
    }
}