#include #include // ENTER 3 DIGITS OR 4 DIGITS NUMBER AS INPUT // int largeno(int n) { int a1[10], len = 0; //int to int array while (n > 0) a1[len] = n % 10, n /= 10, len++; //sorting in descending order// for (int k = 0; k < len; k++) for (int j = 0; j < len; j++) if (a1[k] > a1[j]) { int temp = a1[k]; a1[k] = a1[j]; a1[j] = temp; } //convert to string(so to convert int array to int)// std::string ans; for (int k = 0; k < len; k++) ans += std::to_string(a1[k]); return stoi(ans); } int smallno(int n) { int a2[10], no = largeno(n), len1 = 0; while (no > 0) a2[len1] = no%10, no /= 10, len1++; std::string ans2; for (int k = 0; k < len1; k++) ans2 += std::to_string(a2[k]); return stoi(ans2); } int main(void) { int number, result = 0; std::cin >> number; if(number < 100 || number > 9999){ std::cout << "You entered: " << number << "\n"; std::cout << "ENTER 3 DIGITS OR 4 DIGITS NUMBER AS INPUT.\n"; } else{ std::cout << "You entered: " << number << "\n****************************\n"; while(result!=495&&result!=6174){ result = largeno(number) - smallno(number); if(result==495 || result==6174) std::cout << largeno(number) << " - " << smallno(number) << " = (" << result << ")->magic number."; else std::cout << largeno(number) << " - " << smallno(number) << " = " << result << "\n"; number = result; }} }

Kaprekar's Constants(both 495 6174)