Excel Sheet Column Number.md

#Excel Sheet Column Number ##Problem: 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 

##Idea: 类似于26进制数

class Solution {
public:
    int titleToNumber(string s) {
        int col=0;
        for(int i=0;i<s.length();i++)
        {
            col += pow(26,s.length()-1-i)*(s[i]-'A'+1);
        }
        return col;
    }
};

##To Study:

class Solution {
public:
    int titleToNumber(string s) {
        int col=0;
        for(int i=0;i<s.length();i++)
        {
            col = col*26+s[i]-'A'+1;
        }
        return col;
    }
};