NBU 2019 04. Avtomatichna proverka (calculator)

// Rabotqt i dvata testa v hacker rank - https://www.hackerrank.com/contests/fourth-interuniversity-nbu-programming-contest/challenges/challenge-1894
// tochki ot 100 - ???
#include <iostream>
#include <string>
#include <cstdlib>
#include <sstream>      // std::stringstream

using namespace std;

#define ADDITION 1
#define SUBSTRACTION 2
#define MULTIPLICATION 3
#define DIVISION 4


int state = 0;
int signPosition =0;
int equalSignPosition = 1;


long sstoi(const char *s) // custom stoi function
{
    long i;
    i = 0;
    while(*s >= '0' && *s <= '9')
    {
        i = i * 10 + (*s - '0');
        s++;
    }
    return i;
}

int getFirstNumber(string input, int signPos)
{
    string newString = input.substr(0,signPos);
    int firstNum = sstoi(newString.c_str());
    return firstNum;
    cout << "Return first num: " << firstNum << endl;
}

int getSecondNumber(string input, int signPos)
{
    string newString = input.substr(signPos+1, equalSignPosition-signPosition-1);
    int secondNum = sstoi(newString.c_str());
    return secondNum;
}

int getThirdNumber(string input, int equalSignPos)
{
    string newString = input.substr(equalSignPos+1);
    int thirdNumber = sstoi(newString.c_str());
    return thirdNumber;
}
double solve(double firstNum, double secondNum, double thirdNum)
{
    double trueOrNot = 0;
    switch(state)
    {
     case ADDITION:
     if(firstNum+secondNum==thirdNum)
        trueOrNot = 1;
     break;

     case SUBSTRACTION:
     if(firstNum-secondNum==thirdNum)
        trueOrNot =1;
     break;

     case MULTIPLICATION:
     if(firstNum*secondNum==thirdNum)
        trueOrNot = 1;
     break;

     case DIVISION:
     if(firstNum/secondNum==thirdNum)
        trueOrNot =1;
     break;

    }

 return trueOrNot;


}

int main() {

string input;
string word;

    while(getline(cin, input)){
   // cin.ignore();
    if(input.empty())
        break;

    equalSignPosition = input.find('=');
    if(input.find('+')!=-1)
    {
        state = ADDITION;
        signPosition = input.find('+');
    }

    if(input.find('-')!=-1)
    {
        state = SUBSTRACTION;
        signPosition = input.find('-');
    }

    if(input.find('x')!=-1)
    {
       state = MULTIPLICATION;
       signPosition = input.find('x');
    }

    if(input.find(':')!=-1)
    {
       signPosition = input.find(':');
       state = DIVISION;
    }


    int firstNum = getFirstNumber(input, signPosition);
    int secondNum = getSecondNumber(input,signPosition);
    int thirdNumber = getThirdNumber(input,equalSignPosition);
    double result = solve(firstNum,secondNum,thirdNumber);
    if(result)
        cout <<"Correct" << endl;
    else
        cout <<"Incorrect" << endl;

    }



}