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.

1. int titleToNumber(string s) {
2. int result = 0;
3. int size = s.size();
4. if(size == 0) {
5. return 0;
6. }
7. for(int i=0;i<size;i++) {
8. result = result * 26 + (s.at(i)-'A' + 1);
9. }
10. return result;
11. }