Excel Sheet Column Number

 

 Excel Sheet Column Number

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 
    ...

Example 1:

Input: "A"
Output: 1

Example 2:

Input: "AB"
Output: 28

Example 3:

Input: "ZY"
Output: 701

 

Constraints:

• 1 <= s.length <= 7
• s consists only of uppercase English letters.
• s is between "A" and "FXSHRXW"

 

 class Solution {
public:
    int titleToNumber(string s) {
        int l=0,i=s.size()-1,k=0;
        while(i>=0)
        {
            l=l+(s[i]-'A'+1)*pow(26,k);
                --i;
            ++k;
        }
        return l;
    }
};