Add project files.

Form1.cs

@@ -0,0 +1,83 @@
+namespace Traffic_Light
+{
+    public partial class Form1 : Form
+    {
+        int state = 1;
+        bool reverse = false;
+        int borderSize = 10;
+
+        public Form1()
+        {
+            InitializeComponent();
+        }
+
+        public void Switch()
+        {
+            if (state == 3) reverse = true;
+            if (state == 1) reverse = false;
+
+            if (reverse)
+            {
+                state--;
+            }
+            else
+            {
+                state++;
+            }
+
+            Invalidate();
+        }
+
+        protected override void OnPaint(PaintEventArgs e)
+        {
+            base.OnPaint(e);
+
+            Graphics g = e.Graphics;
+
+            var brush = new SolidBrush(Color.Black);
+            var pen = new Pen(Color.Black, borderSize);
+
+            g.DrawRectangle(pen,
+                50,
+                50,
+                50,
+                150
+            );
+
+            brush.Color = Color.Gray;
+
+            g.FillRectangle(brush,
+                50,
+                50,
+                50,
+                150
+           );
+
+            g.FillRectangle(brush, 50, 50, 50, 150);
+
+            if (state == 1)
+            {
+                brush.Color = Color.Green;
+                g.FillEllipse(brush, 50, 50, 50, 50);
+                return;
+            }
+            if (state == 2)
+            {
+                brush.Color = Color.Yellow;
+                g.FillEllipse(brush, 50, 100, 50, 50);
+                return;
+            }
+            if (state == 3)
+            {
+                brush.Color = Color.Red;
+                g.FillEllipse(brush, 50, 150, 50, 50);
+                return;
+            }
+        }
+
+        private void btn_switch_Click(object sender, EventArgs e)
+        {
+            Switch();
+        }
+    }
+}