Excel Sheet Column Number

题目如下：

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 static int titleToNumber(String s) {
char[] ss = s.toCharArray();
int length = ss.length;
int len = length;
int sum = 0;
for(int i =0;i <length;i++){
sum = sum * 26;
sum = sum +switchInt(ss[i]);
}

return sum;
}

public static int switchInt(char ss){

switch (ss){
case 'A' : return 1;
case 'B' : return 2;
case 'C' : return 3;
case 'D' : return 4;
case 'E' : return 5;
case 'F' : return 6;
case 'G' : return 7;
case 'H' : return 8;
case 'I' : return 9;
case 'J' : return 10;
case 'K' : return 11;
case 'L' : return 12;
case 'M' : return 13;
case 'N' : return 14;
case 'O' : return 15;
case 'P' : return 16;
case 'Q' : return 17;
case 'R' : return 18;
case 'S' : return 19;
case 'T' : return 20;
case 'U' : return 21;
case 'V' : return 22;
case 'W' : return 23;
case 'X' : return 24;
case 'Y' : return 25;
case 'Z' : return 26;
default:return  0;

}
}

public  static void main(String[] args){
String ss = "AB";
int sum = titleToNumber(ss);
System.out.println(sum);
}
}