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

Solution:

This is an easy question. Just like Hex converting to Decimal.
Note: If we use a pointer i reversely go through the array (convert from the given string), the order of 26 should be the "distance" between current pointed element and the last element.

public class Solution 
{
    public int titleToNumber(String s) 
    {
        int result = 0;
        char[] strArray = s.toCharArray();
        for(int i = s.length() - 1; i >= 0; i--)
        {
            result += (Math.pow(26, s.length() - 1 - i) * ((int)strArray[i] - 'A' + 1));
        }
        return result;
    }
}