3. Algebra Helper

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

using namespace std;
bool sortInRev(const pair<int, string>& a, const pair<int, string>& b)
{
    return (a.first > b.first);
}

int main()
{
    int numberOfEquations;
    cin >> numberOfEquations;
    cin.ignore();
    vector<pair<double, string>> memory;

    for (int i = 0; i < numberOfEquations; i++)
    {
        string equation;
        getline(cin, equation);

        double first = 0.0;
        string operation;
        double second = 0.0;
        istringstream istr(equation);
        istr >> first >> operation >> second;

        double result = 0.0;
        if (operation == "+")
        {
            result = first + second;
        }
        else if (operation == "-")
        {
            result = first - second;
        }
        else if (operation == "*")
        {
            result = first * second;
        }
        else if (operation == "/")
        {
            result = first / second;
        }
        else
        {
            result = int(first) % int(second);
        }

        memory.push_back(pair<double, string>(result, equation));
    }

    sort(memory.begin(), memory.end(), sortInRev);

    for (int i = 0; i < memory.size(); i++)
    {
        cout << memory[i].second << endl;
    }
    return 0;
}