#include <iostream>
#include <iomanip>
#include <unordered_map>
#include <string>
#include <cstdlib>
using namespace std;

using Fraction = pair<int,int>;

ostream& operator<<(ostream& out, const Fraction& f)
{
   out << f.first << '/' << f.second;
   return out;
}

//function templates
template <typename F, typename S>
ostream& operator<<(ostream& out, const pair<F,S>& p)
{
   out << "first: " << p.first << "  second: " << p.second;
   return out;
}

template <typename K, typename V>
ostream& operator<<(ostream& out, const unordered_multimap<K,V>& m)
{
   for (auto element : m) out << element << endl;
   return out;
}

int main()
{
   unordered_multimap<double,Fraction> fractions;

   fractions.insert(pair<double,Fraction>(.75,Fraction(3,4)));
   fractions.insert(pair<double,Fraction>(.75,Fraction{6,8}));
   Fraction neg_3_4{-3,-4};
   fractions.insert(pair<double,Fraction>(.75,neg_3_4));

   Fraction temp_fraction;
   pair<double,Fraction> temp_doub_fraction;

   temp_fraction = {1,2};
   temp_doub_fraction = {.5,temp_fraction};
   fractions.insert(temp_doub_fraction);
   fractions.insert({.5,{2,4}});
   fractions.insert({.33,{1,3}});
   fractions.insert({.25,{1,4}});
   fractions.insert({.5,{1,2}});
   cout << fractions << endl;

   // fractions[.4] = fraction(2,5);  // Error: no index operator

   // find
   unordered_multimap<double,Fraction>::const_iterator cIt;
   cout << "fractions.find(.33): ";
   cIt = fractions.find(.33);
   cout << *cIt << endl;
   cout << "fractions.find(.75): " << *fractions.find(.75) << endl;
   cout << "fractions.find(.55):  ";
   cIt = fractions.find(.55);
   // check to make sure find is OK
   if (cIt == fractions.end())
      cout << "Can't find .55" << endl << endl;

   // count
   cout << "fractions.count(.5)=" << fractions.count(.5) << endl;
   cout << "fractions.count(.6)=" << fractions.count(.6) << endl
        << endl;

   // equal_range
   cout << "equal range(.5): " << endl;
   auto iters = fractions.equal_range(.5);
   cout << *(iters.first) << " / " << *(iters.second) << endl;
   for (auto iter = iters.first; iter != iters.second; ++iter)
      cout <<  *iter << endl;
   cout << endl;

   // erase
   cout << "fractions.erase(.33) = " << fractions.erase(.33) << endl;
   cout << "fractions.erase(.5) = " << fractions.erase(.5) << endl;
   cout << "fractions.erase(.55) = " << fractions.erase(.55) << endl << endl;
   cout << fractions << endl;
}