问题描述：

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 

代码：

int titleToNumber(string s) {
        int num = 0;
        if(s.size() == 0)
            return 0;
             
        map<char,int> myMap;
        for(int i = 1; i <=26; i++)
        {
            myMap.insert(make_pair('A'+i-1,i));
        }
         
        for(int i = 0; i < s.size(); i++)
        {
            char ch = s[i];
            num = num*26+myMap[ch];
        }
        return num;
    }

[leetcode]