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 

Credits:

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

#include <iostream>
#include <string>
using namespace std;


class Solution {
public:
    int titleToNumber(string s) {
        int sum = 0;
        for(int i = 0; s[i] != '\0'; i++)
{
       
            sum = sum *26 + (s[i] - 'A' + 1);//看作26进制
        }
        cout << endl;
        return sum;
   
    }
};