02. Visteon Luhn Algorithm (checksum)

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;


int sumDigits(int inputNumber)
{
    int firstDigit = inputNumber / 10;
    int secondDigit = inputNumber % 10;
    return firstDigit + secondDigit;
}


int LuhnAlgorithm(string inputString)
{
    int currentNumber = 0;
    int sum = 0;
    for(int i =0; i<inputString.size();i++)
    {
        currentNumber = int(inputString.at(i)) - 48;
        if(i % 2 == 1)
        {
            currentNumber *= 2;
        }
        if(currentNumber >=10)
        {
            sum += sumDigits(currentNumber);
        }
        else
        {
            sum += currentNumber;

        }
    }
    cout << sum << endl;
    if(sum % 10  == 0)
        return 1;
    return 0;

}

int main()
{
    string str = "354557030810924";
    cout << LuhnAlgorithm(str) << endl;

}