[leedcode 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) {
        //26进制转化为十进制，从输入值的高位向低位计算
        if(s==null||s.length()<=0) return 0;
        int res=0;
        for(int i=0;i<s.length();i++){
            res=res*26+s.charAt(i)-'A'+1;
        }
        return res;
    }
}