diff --git a/Class Examples/mutex.cs b/Class Examples/mutex.cs
new file mode 100644
index 0000000..ff93d3d
--- /dev/null
+++ b/Class Examples/mutex.cs	
@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+
+namespace mutexexample2
+{
+    class Program
+    {
+        public static Mutex m = new Mutex();
+        public static readonly int LOOP = 50000;
+        public static long gvar = 0;
+
+        static public void produce()
+        {
+            m.WaitOne();
+            for (int i = 0; i < LOOP; i++)
+                gvar++;
+            m.ReleaseMutex();
+        }
+
+        static public void consume()
+        {
+            m.WaitOne();
+            for (int i = 0; i < LOOP; i++)
+                gvar--;
+            m.ReleaseMutex();
+        }
+
+        static void Main(string[] args)
+        {
+            Thread t1 = new Thread(new ThreadStart(produce));
+            t1.Start();
+
+            Thread t2 = new Thread(new ThreadStart(consume));
+            t2.Start();
+
+            t1.Join();
+            t2.Join();
+
+            Console.WriteLine(gvar);
+        }
+    }
+}
diff --git a/Class Examples/node-generic.cs b/Class Examples/node-generic.cs
new file mode 100644
index 0000000..46ec617
--- /dev/null
+++ b/Class Examples/node-generic.cs	
@@ -0,0 +1,67 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace generics
+{
+    class Program
+    {
+        class Node<T>  where T : System.IComparable<T>
+        {
+            public T element;
+            public Node<T> left = null;
+            public Node<T> right = null;
+            Node<T> parent = null;
+
+            public Node<T> createNode(T element)
+            {
+                Node<T> n = new Node<T>() { parent = this, element = element };
+                return n;
+            }
+
+            public Node<T> addLeft(T element)
+            {
+                this.left = createNode(element);
+                return this.left;
+            }
+            public Node<T> addRight(T element)
+            {
+                this.right = createNode(element);
+                return this.right;
+            }
+            public override string ToString()
+            {
+                return "Node element => " + element.ToString();
+            }
+            
+        }
+        static Node<T> dfs<T>(T val, Node<T> parent) where T : System.IComparable<T>
+        {
+            if (parent == null)
+                return null;
+
+            if (parent.element.CompareTo(val) == 0)
+                return parent;
+
+            Node<T> ret = null;
+            if (parent.left != null)
+                ret = dfs(val, parent.left);
+            if (ret != null)
+                return ret;
+            if (parent.right != null)
+                ret = dfs(val, parent.right);
+            if (ret != null)
+                return ret;
+            return null;
+        }
+        static void Main(string[] args)
+        {
+            Node<int> n = new Node<int>();
+            n.addLeft(4).addLeft(10).addLeft(7);
+            n.addRight(5).addRight(2);
+            Console.WriteLine(dfs(2, n));
+
+        }
+    }
+}
diff --git a/Class Examples/node.cs b/Class Examples/node.cs
new file mode 100644
index 0000000..72e78cd
--- /dev/null
+++ b/Class Examples/node.cs	
@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace generics
+{
+    class Program
+    {
+        class Node
+        {
+            public int element;
+            public Node left = null;
+            public Node right = null;
+            Node parent = null;
+
+            public Node createNode(int element)
+            {
+                Node n = new Node() { parent = this, element = element };
+                return n;
+            }
+
+            public Node addLeft(int element)
+            {
+                this.left = createNode(element);
+                return this.left;
+            }
+            public Node addRight(int element)
+            {
+                this.right = createNode(element);
+                return this.right;
+            }
+            public override string ToString()
+            {
+                return "Node element => " + element.ToString();
+            }
+        }
+        static Node dfs(int val, Node parent)
+        {
+            if (parent == null)
+                return null;
+
+            if (parent.element == val)
+                return parent;
+
+            Node ret = null;
+            if (parent.left != null)
+                ret = dfs(val, parent.left);
+            if (ret != null)
+                return ret;
+            if (parent.right != null)
+                ret = dfs(val, parent.right);
+            if (ret != null)
+                return ret;
+            return null;
+        }
+        static void Main(string[] args)
+        {
+            Node n = new Node();
+            n.addLeft(4).addLeft(10).addLeft(7);
+            n.addRight(5).addRight(2);
+            Console.WriteLine(dfs(22, n));
+
+        }
+    }
+}
diff --git a/Class Examples/produce-consume.cs b/Class Examples/produce-consume.cs
new file mode 100644
index 0000000..9a09a4a
--- /dev/null
+++ b/Class Examples/produce-consume.cs	
@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+
+namespace mutexexample2
+{
+    class Program
+    {
+        public static readonly int LOOP = 50000;
+        public static long gvar = 0;
+
+        static public void produce()
+        {
+            for (int i = 0; i < LOOP; i++)
+                gvar++;
+        }
+
+        static public void consume()
+        {
+            for (int i = 0; i < LOOP; i++)
+                gvar--;
+        }
+
+        static void Main(string[] args)
+        {
+            Thread t1 = new Thread(new ThreadStart(produce));
+            t1.Start();
+
+            Thread t2 = new Thread(new ThreadStart(consume));
+            t2.Start();
+
+            t1.Join();
+            t2.Join();
+
+            Console.WriteLine(gvar);
+        }
+    }
+}
diff --git a/Class Examples/swap.cs b/Class Examples/swap.cs
new file mode 100644
index 0000000..055823e
--- /dev/null
+++ b/Class Examples/swap.cs	
@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace generics
+{
+    class Program
+    {
+        static void swap<T>(ref T lhs,ref T rhs)
+        {
+            T temp;
+            temp = lhs;
+            lhs = rhs;
+            rhs = temp;
+        }
+        static void Main(string[] args)
+        {
+            int a, b;
+            a = 10;
+            b = 20;
+            Console.WriteLine(a.ToString() + " " + b.ToString());
+            swap(ref a, ref b);
+            Console.WriteLine(a.ToString() + " " + b.ToString());
+
+        }
+    }
+}