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

26进制

class Solution {
public:
int titleToNumber(string s) {
int tmp=0,sum=0;
for(int i=0;i<s.size();i++)
{
tmp=s[i]-'A'+1;
sum=sum*26+tmp;
}
return sum;
}
};