#include <windows.h>
#include <iostream>
#define NumThread 9
#define dokladnosc 9999999999
using namespace std;


HANDLE mutex;
struct Dane
{
    double pi;
    int i;
    int arg;
};

double pi(int n) {
    double sum = 0.0;
    int sign = 1;
    for (int i = 0; i < n; ++i) {
        sum += sign / (2.0*i + 1.0);
        sign *= -1;
    }
    return 4.0*sum;
}
DWORD WINAPI watek(LPVOID LpParam) {
    Dane* dane = (Dane*)LpParam;

    WaitForSingleObject(mutex, INFINITE);
    while(dane->i < dokladnosc)
    {
        dane->pi += dane->arg / (2.0*dane->i +1);
        dane->arg *= -1;
        dane->i++;
    }
    ReleaseMutex(mutex);
    cout << "exit" << endl;

    return 0;
}

int main()
{
    DWORD id;
    Dane* dane = new Dane(); HANDLE w[NumThread];

    dane->arg = 1;
    dane->pi = 0;
    dane->i = 0;
    mutex = CreateMutex(NULL, false, NULL);

    cout << pi(dokladnosc)<<endl;

    for (int i = 0; i < NumThread; ++i)
    {
        w[i] = CreateThread(NULL, 0, watek, dane, 0, &id);
    }

    WaitForMultipleObjects(NumThread, w, true, 10000);
    cout << dane->pi*4 << endl;

    for (int i = 0; i < NumThread; ++i)
    {
        CloseHandle(w[i]);
    }
}