/* A Voodoo prime is a prime number whose reciprocal (in decimal) has the same number in its digits. For example, 7 is a voodoo prime because its reciprocal 1/7=0.14285714285 contains 7. Examples: Input: 3 Output: true (1/3=0.33333333333 contains 3) Input: 11 Output: false (1/11=0.0909090909 doesn't contain 11) Write a program to check if the user input is a Voodoo prime or not. */ #include #include #include #include using namespace std; bool isVoodooPrime(const size_t& number); bool isPrime(const size_t& number); int main() { size_t range_begin; size_t range_end; // range of the numbers to be checked cin >> range_begin >> range_end; //if first number in range greater than second //just swap them if(range_begin > range_end) { swap(range_begin, range_end); } cout << "All voodoo numbers in: " << range_begin << " - " << range_end << ": " << endl << endl; // set max standard precision for floating point number cout.precision(6); cout.setf(ios::fixed); for(size_t i = range_begin; i <= range_end; ++i) { if(!isPrime(i)) { continue; } if(isVoodooPrime(i)) { cout << i << " - is voodoo prime: " << 1.0L / i; } else { cout << i << " - is not voodoo prime: " << 1.0L / i; } cout << endl; } return 0; } bool isVoodooPrime(const size_t& number) { //inverse number string inumber = to_string(1.0L / number); //pattern for regex; string pattern = R"([0-9]+\.[0-9]*)" + to_string(number) + "[0-9]*"; //regex for searching for our number regex voodoo(pattern.c_str()); return regex_search(inumber.c_str(), voodoo); } bool isPrime(const size_t& number) { if(number == 2) { return true; } //even number cannot be prime else if(number % 2 == 0) { return false; } for(size_t i = 2; i < number / 2; ++i) { if(number % i == 0) { return false; } } return true; }

[Assignment] Vodoo Primes