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".

Solutions

🧠 Cpp

class Solution {
public:
    int titleToNumber(string s)
    {
        int res = 0;
        int index = 0;
        for(auto riter = s.rbegin(); riter != s.rend(); ++riter, ++index)
            res+= (*riter-'A'+1)*std::pow(26,index);
        return res;
    }
};