/*
 Author:     King, wangjingui@outlook.com
 Date:       Dec 28, 2014
 Problem:    Excel Sheet Column Number
 Difficulty: Medium
 Source:     https://oj.leetcode.com/problems/excel-sheet-column-number/
 Notes:
 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 

 Solution: 1. ...
*/

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