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;
    }
};