private void btnClear_Click(object sender, EventArgs e)
{
listVertex.Clear();
ListEdge.Clear();
numberV = 0;
g.Clear(Color.White);
bHD = false;
txtg.Hide();
Invalidate();
}
private void btnhd_Click(object sender, EventArgs e)
{
//xoa het
listVertex.Clear();
ListEdge.Clear();
numberV = 0;
g.Clear(Color.White);
//bat huong dan
TextHuongDan(g);
bHD = true;
}