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

//一道自定义进制转换的问题，26进制转10进制

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