Leetcode 171. Excel Sheet Column Number (Easy) (cpp)

/*

171. Excel Sheet Column Number (Easy)

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

*/
class Solution {
public:
int titleToNumber(string s) {
int res = 0;
for (int i = 0; i < s.length(); i++) {
res = res * 26 + (s[i] - '@');
}
return res;
}
};