#include <QCoreApplication>
#include <QThread>
#include <QDebug>

/*
 * sum(n) = 1 + 2 + 3 + ... + n
 * sum(1000) ==>分解成3个任务
 *          [1, 1000] = [1, 300] [301, 600] [601, 1000]
 */

class Calculator : public QThread
{
protected:
    int m_begin;
    int m_end;
    int m_result;

    void run()
    {
        qDebug() << objectName() << " : run() begin";

        for(int i=m_begin; i<=m_end; i++)
        {
            m_result += i;
            msleep(10);
        }

         qDebug() << objectName() << " : run() end";
    }

public:
    Calculator(int begin, int end)
    {
        m_begin = begin;
        m_end = end;
        m_result = 0;
    }

    //模拟串行解决方案
    void work()
    {
         run();
    }

    int getResult()
    {
        return m_result;
    }
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    qDebug() << "main begin";

    Calculator cal1(1, 300);    //任务1
    Calculator cal2(301, 600);  //任务2
    Calculator cal3(601, 1000); //任务3

    cal1.setObjectName("cal1");
    cal2.setObjectName("cal2");
    cal3.setObjectName("cal3");

    //模拟串行解决方案（将run函数作为一般的成员函数调用）
    //cal1.work();  //先完成任务1
    //cal2.work();  //再完成任务2
    //cal3.work();  //最后完成任务3
    //int result = cal1.getResult() + cal2.getResult() + cal3.getResult();
    //qDebug() << "result = " << result;

    //并行解决方案（利用多线程解决）
    cal1.start(); //启动线程1
    cal2.start(); //启动线程2
    cal3.start();  //启动线程3

    cal1.wait();  //等待线程1结束
    cal2.wait();  //等待线程2结束
    cal3.wait();  //等待线程3结束

    int result = cal1.getResult() + cal2.getResult() + cal3.getResult();//必须等三个子线程结束后再进行结果的相加，否则将出现错误
    qDebug() << "result = " << result;

    qDebug() << "main end";

    return a.exec();
}