add example code

Author: exuuguu

ListNode.java

@@ -0,0 +1,13 @@
+public class ListNode{
+    private int val;
+    public ListNode next;
+
+    public ListNode(final int val){
+        this.val = val;
+        this.next = null;
+    }
+
+    public int value(){
+        return this.val;
+    }
+}

TreeNode.java

@@ -0,0 +1,13 @@
+public class TreeNode{
+    private int val;
+    public TreeNode left, right;
+
+    public TreeNode(final int val){
+        this.val = val;
+        this.left = this.right = null;
+    }
+
+    public int value(){
+        return this.val;
+    }
+}