Excel Column Address problem | CPP | C++

excelColumnaddress.cpp

#include <iostream>
#include <math.h>
#define TOTAL 26

/*
Logic
	Lets take the example of "A B C"
	Let answer = 0
	
	Our String size is 3.   
	To reach string size 3 we must have used all combinations possible of length 2. 
	Which means 26*26 combinations we have seen to have string length of 3. 
	Our CHARACTER 1 is A, this means we have seen 26*26 combination just once.
	So we update our answer += 1*26*26 = 676;
	
	Now we jump to second CHARACTER B. Same process, we reached to length 2 after we have seen all combinations of length 1 i.e 26 combinations
	Our CHARACTER is B which means we have seen 26 combination 2 times.
	So  answer += 26*2 = 728
	
	Now we jump to last CHARACTER C,nothing after that so we just add it
	So answer += 3 = 731;
	
	In short
	26^ 2 * A + 26^1 * B + 26^0 * C = 731
	
*/

int address(std::string cell)
{
	int ads = 0;
	
	for(int i=cell.size(), j=0; i>0 ; i--,j++){
		int a = cell[j] - 64;
		ads += (pow(TOTAL,i-1) * a);
	}
	return ads;
}

/*
	logic
	
	This is just optimised version of above.
	
	if you look closely .
	26^ 2 * A + 26^1 * B + 26^0 * C = 731
	
	It look same as we convert Base(x) to Base(10)
	example 101 is 5 in Base 2
	
	1*2^2 + 0*2^1 + 1*2^0 = 5
    Below code is just converting Base(26) to Base(10)
*/

int alternate(std::string cell)
{
	int ads = cell[0] -64;
	for(int i=0; i<cell.size()-1; i++){
		int n = cell[i+1] -64;
		ads = TOTAL*ads + n; 
	}
	return ads;
}


int main()
{
	std::string cell;
	std::cin >> cell;
	std::cout << address(cell) << '\n';
	std::cout << alternate(cell) << '\n';
}