testsAndMisc/CPP/miscelanious/howManyValidISBNNumbersAreThere/11.cpp

#include <algorithm>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>

#ifndef CHECK_ISBN_CPP
#define CHECK_ISBN_CPP

const bool DEBUG = 0;
const int ISBN_LENGTH = 10;
const int CHECK_NUMBER = 11;
const unsigned long long int HIGHEST_ISBN = 9999999999;

void printVector(std::vector<int> v) {
  for (unsigned int i = 0; i < v.size(); i++) {
    std::cout << v[i] << "; ";
  }
}

void print(const std::string printMe) { std::cout << printMe << std::endl; }

void e() { print("PRINT"); }

bool checkInput(const std::string input) {
  if (input.length() != ISBN_LENGTH) {
    print("Your number is too short/too long");
    return 0;
  }
  for (int i = 0; i <= ISBN_LENGTH - 1; i++) {
    if (input.at(i) < '0' || input.at(i) > '9') {
      print("Your number consists of illegal characters");
      return 0;
    }
  }
  return 1;
}

std::vector<int> stringToIntVector(const std::string input) {
  std::vector<int> vector;
  for (int i = input.length() - 1; i >= 0; i--) {
    vector.push_back(input.at(i) - '0');
  }
  return vector;
}

std::vector<int> userISBN() {
  std::string input;
  do {
    std::cout << "Enter the ISBN number (10 digits): ";
    getline(std::cin, input);
  } while (!checkInput(input));
  return stringToIntVector(input);
}

bool checkISBN(const std::vector<int> isbn) {
  int sum = 0, t = 0;
  for (int i = 0; i < ISBN_LENGTH; i++) {
    t += isbn[i];
    sum += t;
  }

  /*if(DEBUG)
  {
          if(!(sum % CHECK_NUMBER)) print("^^^ VALID NUMBER ^^^");
  } */

  return !(sum % CHECK_NUMBER);
}

std::vector<int> intToVector(unsigned long long int number) {
  std::vector<int> numbers;
  while (number > 0) {
    numbers.push_back(number % 10);
    number /= 10;
  }
  std::reverse(numbers.begin(), numbers.end());

  return numbers;
}

int checkAll() {
  int sum = 0;
  std::ofstream file;
  file.open("ISBN.txt");
  for (unsigned long long int i = HIGHEST_ISBN; i >= 1; i--) {
    // if(DEBUG) std::cout << i << std::endl;
    if (checkISBN(intToVector(i))) {
      ++sum;
      file << std::to_string(i) << "\n";
    }
  }
  file << "There are " << sum << " valid ISBN numbers\n";
  file.close();
  return sum;
}

int main() {
  checkAll();
  return 0;
}

#endif