Excel Sheet Column Number | Problem No. 171 | LeetCode

Given a column title as appearing 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) {
        long int res=0, i=s.length()-1,temp=1;
        for( ;i>=0;i--){
            res=res + temp*(s[i]-'A'+1);
            temp*=26;
        }
        return res;
    }
};