Related to question Excel Sheet Column Title

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

1
2
3
4
5
6
7
A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28
1
2
3
4
5
6
7
8
9
10
11
12
public class Solution {
    public int titleToNumber(String s) {
        if (s == null || s.length() < 1){return 0;}
        int col = 0;
        for (int i = 0; i < s.length(); i++){
            char cur = s.charAt(i);
            if (cur < 'A' || cur > 'Z'){return 0;} // corner case
            col = col * 26 + (int) (cur - 'A' + 1);
        }
        return col;
    }
}