Inorder, postorder and preorder tree traversal added in kotlin

Kotlin/treeDepthtraversal.kt

@@ -0,0 +1,87 @@
+/**
+ * program will create Binary search tree from given inputs and print them
+ in Postorder, Preorder and inorder in kotlin.
+
+ *  Binary search tree is a binary tree in which node having child at left is
+ less than node and child at right is higher than node.
+
+ * Postorder - (Left, Right, Root)
+ * Preorder - (Root, Left, Right)
+ * Inorder -  (Left, Root, Right)
+ **/
+
+
+class Node(
+    var key: Int,
+    var left: Node? = null,
+    var right: Node? = null){
+
+    /* this method will insert node in BST*/
+    fun insert(value: Int) {
+        if (value > this.key) {
+            if (this.right == null) {
+                this.right = Node(value)
+            } else {
+                this.right!!.insert(value)
+            }
+        } else if (value < this.key) {
+            if (this.left == null) {
+                this.left = Node(value)
+            } else {
+                this.left!!.insert(value)
+            }
+        }
+    }
+
+    /* this method will print tree in postorder*/
+    fun postOrderPrint(){
+        this.left?.postOrderPrint()
+        this.right?.postOrderPrint()
+        print(this.key.toString()+" ")
+    }
+
+    /* this method will print tree in preorder*/
+    fun preOrderPrint(){
+        print(this.key.toString()+" ")
+        this.left?.preOrderPrint()
+        this.right?.preOrderPrint()
+    }
+
+    /* this method will print tree in inorder*/
+    fun inOrderPrint(){
+        this.left?.inOrderPrint()
+        print(this.key.toString()+" ")
+        this.right?.inOrderPrint()
+    }
+}
+
+
+fun main(args: Array<String>){
+
+    println("Enter Nodes to create Binary Search Tree - ")
+
+    val keys = readLine()!!.split(' ').run { IntArray(size) { get(it).toInt() } } // read nodes from input
+
+    var tree : Node? = null
+
+    for (key in keys) {
+        if (tree == null) {
+            tree = Node(key)
+        }else{
+            tree.insert(key)
+        }
+    }
+
+    println("Preorder of tree - ")
+    tree?.postOrderPrint()
+    println("")
+
+    println("Pretorder of tree - ")
+    tree?.preOrderPrint()
+    println("")
+
+    println("inorder of tree - ")
+    tree?.inOrderPrint()
+    println("")
+
+}