ExcelColumnNumber.cpp

/*

https://www.interviewbit.com/problems/excel-column-number/


Given a column title as appears in an Excel sheet, return its corresponding column number.

Example:

 A -> 1
 
 B -> 2
 
 C -> 3
 
 ...
 
 Z -> 26
 
 AA -> 27
 
 AB -> 28 

*/


int Solution::titleToNumber(string A) 
{
 // Do not write main() function.
 // Do not read input, instead use the arguments to the function.
 // Do not print the output, instead return values as specified
 // Still have a doubt. Checkout www.interviewbit.com/pages/sample_codes/ for more details

 int res=0;
 
 for(auto ch : A)
 {
 res *= 26;
 res += ch-'A'+1;
 }
 return res; // O(n), O(1)
}