LeetCode OJ 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

Credits: Special thanks to @ts for adding this problem and creating all test cases.

class Solution {

public:

int titleToNumber(string s) {

int sum = 0;

int base = 1;

for (int i = s.size() - 1; i >= 0; i--) {

sum += base * (s[i] - 'A' + 1);

base *= 26;

}

return sum;

}

};