magic_dates.cpp

#include <iostream>

using namespace std;

bool checkAddition(int y, int m, int d);
bool checkMultiply(int y, int m, int d);
bool checkDivision(int y, int m, int d);
bool checkSubstraction(int y, int m, int d);

bool checkAddition(int y, int m, int d) {
  return y == m + d;
}

bool checkSubstraction(int y, int m, int d) {
  return y == m - d;
}

bool checkMultiply(int y, int m, int d) {
  return y == m * d;
}

bool checkDivision(int y, int m, int d) {
  return static_cast<float>(y) == static_cast<float>(d) / static_cast<float>(m);
}

int main() {
  int special = 0;
  int extra = 0;
  
  int counter = 0;
  int addCounter = 0;
  int subCounter = 0;
  int mulCounter = 0;
  int divCounter = 0;

  int months[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

  for (int y=0; y<100; y++) {
    if (y%400==0 || (y%100 != 0 && y%4 == 0)) {
      months[1] = 29;
    } else {
      months[1] = 28;
    }
    for (int m=1; m<=12; m++) {
      for (int d=1; d<=months[m-1]; d++) {
	extra = 0;
	if (checkAddition(y, m, d)) {
	  cout << "Add: " << d << "-" << m << "-" << y << " ";
	  addCounter++;
	  extra++;
	}
	if (checkSubstraction(y, m, d)) {
	  cout << "Sub: " << d << "-" << m << "-" << y << " ";
	  subCounter++;
	  extra++;
	}
	if (checkMultiply(y, m, d)) {
	  cout << "Mul: " << d << "-" << m << "-" << y << " ";
	  mulCounter++;
	  extra++;
	}
	if (checkDivision(y, m, d)) {
	  cout << "Div: " << d << "-" << m << "-" << y;
	  divCounter++;
	  extra++;
	}
	if (extra > 1)
	  special++;
	if (extra > 0) {
	  counter++;
	  cout << endl;
	}
      }
    }
  }
  cout << "Adds: " << addCounter << endl;
  cout << "Subs: " << subCounter << endl;
  cout << "Mults: " << mulCounter << endl;
  cout << "Divs: " << divCounter << endl;
  cout << "Number of magic dates: " << counter << endl;
  if (special > 0)
    cout << "Some dates are extra special!" << endl;
    
  return 0;
}