171. 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 

与168题正好相反，26进制数转10进制数。

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