the problem is i need to change color of each rect once swap takes place for example if rect 1 and rect 3 are interchanged they would change to red from yellow then swap values and then change back to normal color

this is the code of my dialog

@
void Dialog::paintEvent(QPaintEvent *e)
{

QPainter painter(this);
QBrush brush(Qt::yellow);
 QBrush brush2(Qt::red);
QPen pen1(Qt::black);
pen1.setWidth(6);
QString str[10];


for(int a=0;a<9;a++)
{
    str[a].append(QString("%1").arg(array[a]));
    QRect rec(((50*a)+50),100,50,50);
    painter.setPen(pen1);
    painter.drawRect(rec);
    painter.fillRect(rec,brush);
    painter.drawText(rec,Qt::AlignCenter,str[a]);

}
delay();
heaped();
//heapify();

QString str2[10];



for(int a=0;a<9;a++)
{
    str2[a].append(QString("%1").arg(array[a]));
    QRect rec(((50*a)+50),100,50,50);
    painter.setPen(pen1);
    painter.drawRect(rec);
    painter.fillRect(rec,brush2);
    painter.drawText(rec,Qt::AlignCenter,str2[a]);


}
 repaint();

delay();

}

@

@void Dialog::heaped()
{

while(flag != 0)
{
    flag = 0;
    for(int i=size-1; i>0; i--)
    {
        int j = i/2;

        if(array[j] > array[i])
        {
            QPaintEvent *e;
            int temp = array[i];
            array[i] = array[j];
            array[j] = temp;
            flag++;
        }
    }
}

}@

@Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
flag=1;
size=9;
for(int i=0;i<9;i++) // code to set values randomly to the array
{
array[i]=(qrand()0)+1;

}
ui->setupUi(this);

}

Dialog::~Dialog()
{
delete ui;
}

void Dialog::delay() // function to give delay
{
QTime time=QTime::currentTime().addSecs(3);
while(QTime::currentTime()<time)
{
QCoreApplication::processEvents(QEventLoop::AllEvents,100);
}

}@