Merge pull request #10 from Jacob3075/dsa-#3-kotlin-btree

Added code for binary tree

Author: swapnita-pandey

Binary Tree/BTree.kt

@@ -0,0 +1,141 @@
+import java.util.LinkedList
+import java.util.Queue
+import java.util.Scanner
+
+class BTree {
+    var root: Node? = null
+    var temp = root
+
+    private fun insert(temp: Node?, key: Int) {
+        var temp = temp
+        if (temp == null) {
+            root = Node(key)
+            return
+        }
+        val q: Queue<Node?> = LinkedList()
+        q.add(temp)
+
+        // Do level order traversal until we find
+        // an empty place.
+        while (!q.isEmpty()) {
+            temp = q.peek()
+            q.remove()
+            if (temp!!.left == null) {
+                temp.left = Node(key)
+                break
+            } else q.add(temp.left)
+            if (temp.right == null) {
+                temp.right = Node(key)
+                break
+            } else q.add(temp.right)
+        }
+    }
+
+    private fun deleteDeepest(root: Node?, delNode: Node?) {
+        val q: Queue<Node?> = LinkedList()
+        q.add(root)
+        var temp: Node? = null
+
+        // Do level order traversal until last node
+        while (!q.isEmpty()) {
+            temp = q.peek()
+            q.remove()
+            if (temp === delNode) {
+                temp = null
+                return
+            }
+            if (temp!!.right != null) {
+                if (temp.right === delNode) {
+                    temp.right = null
+                    return
+                } else q.add(temp.right)
+            }
+            if (temp.left != null) {
+                if (temp.left === delNode) {
+                    temp.left = null
+                    return
+                } else q.add(temp.left)
+            }
+        }
+    }
+
+    // Function to delete given element
+    // in binary tree
+    fun delete(root: Node?, key: Int) {
+        var root: Node? = root ?: return
+        if (root!!.left == null && root.right == null) {
+            if (root.data == key) {
+                root = null
+                return
+            } else return
+        }
+        val q: Queue<Node?> = LinkedList()
+        q.add(root)
+        var temp: Node? = null
+        var keyNode: Node? = null
+
+        // Do level order traversal until
+        // we find key and last node.
+        while (!q.isEmpty()) {
+            temp = q.peek()
+            q.remove()
+            if (temp!!.data == key) keyNode = temp
+            if (temp.left != null) q.add(temp.left)
+            if (temp.right != null) q.add(temp.right)
+        }
+        if (keyNode != null) {
+            val x: Int = temp!!.data
+            deleteDeepest(root, temp)
+            keyNode.data = x
+        }
+    }
+
+    private fun preorder(node: Node?) {
+        // N -> L -> R
+        if (node == null) return
+        print(node.data.toString() + " ")
+        preorder(node.left)
+        preorder(node.right)
+    }
+
+    private fun inorder(temp: Node?) {
+        // L -> N -> R
+        if (temp == null) return
+        inorder(temp.left)
+        print(temp.data.toString() + " ")
+        inorder(temp.right)
+    }
+
+    private fun postorder(node: Node?) {
+        // L -> R -> N
+        if (node == null) return
+        postorder(node.left)
+        postorder(node.right)
+        print(node.data.toString() + " ")
+    }
+
+    fun main(args: Array<String>) {
+        val sc = Scanner(System.`in`)
+        println("Enter the number of node: ")
+        val n = sc.nextInt()
+        for (i in 0 until n) {
+            val k = sc.nextInt()
+            insert(root, k)
+        }
+        println("Preorder Traversal (N -> L -> R): ")
+        preorder(root)
+        println()
+        println("Inorder Traversal (L -> N -> R): ")
+        inorder(root)
+        println()
+        println("Postorder Traversal (L -> R -> N): ")
+        postorder(root)
+        println()
+        sc.close()
+    }
+
+    class Node(var data: Int) {
+        var left: Node? = null
+        var right: Node? = null
+    }
+}