[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;
}
}