LeetCode 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 

Nothing special....

class Solution {    public:    int CharToInteger(char a) {        return a - 64;    }        int titleToNumber(string s) {        int sum = 0;        for(int i = 0; i < s.size(); ++i) {            sum = sum * 26 + CharToInteger(s[i]);        }        return sum;    }};