紅綠燈

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication3
{
    public partial class Form1 : Form
    {
        int i, j;
        public Form1()
        {
            InitializeComponent();
            i = 0;
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            i++;
            i = i % 3;
            label1.Text = Convert.ToString(i);
            button1.Enabled = false;
            button2.Enabled = false;
            button3.Enabled = false;
            j++;
            j = j % 3;
            switch (j)
            {
                case 0:
                    button1.Enabled = true;
                    timer1.Interval = 300;
                    break;
                case 1:
                    button2.Enabled = true;
                    timer1.Interval = 300;
                    break;
                case 2:
                    button3.Enabled = true;
                    timer1.Interval = 3000;
                    break;
            }
        }
    }
}