LeetCode 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 

public class Solution {
    public int titleToNumber(String s) {
        // BAC -> 2*26*26+1*26+3
        // Note: Character.getNumericValue(ch) is used for convert number (e.g, '3' -> 3)
        // (int) is used to get ASCII code (e.g., 'A' -> 65; '3' -> 51)
        int n = s.length();
        int result = 0;
        int nA = 'A';
        
        for (int i = n-1; i >= 0; i--)
            result += Math.pow(26, n-i-1)*(s.charAt(i)-nA+1);
            
        return result;
    }
}