binary tree creation and basic traversal

Author: anuragkmr45

tree/BinaryTree/CreateBT.java

@@ -0,0 +1,31 @@
+package tree.BinaryTree;
+
+public class CreateBT {
+    Node root;
+
+    int index = -1;
+
+    // create Binary treee from array
+    // return root of the tree
+    public Node createTreeFromArr(int[] nodes) {
+        index++;
+        if (nodes[index] == -1) {
+            return null;
+        }
+
+        Node newNode = new Node(nodes[index]);
+        newNode.left = createTreeFromArr(nodes);
+        newNode.right = createTreeFromArr(nodes);
+
+        return newNode;
+    }
+
+    public static void main(String[] args) {
+        int[] nodes = { 9, 2, 4, -1, -1, 5, -1, -1, 3, -1, 6, -1, -1 };
+
+        CreateBT tree = new CreateBT();
+        Node root = tree.createTreeFromArr(nodes);
+
+        System.out.println(root.data);
+    }
+}

tree/BinaryTree/Node.java

@@ -0,0 +1,13 @@
+package tree.BinaryTree;
+
+public class Node {
+    int data;
+    Node left;
+    Node right;
+
+    Node(int data) {
+        this.data = data;
+        this.left = null;
+        this.right = null;
+    }
+}

tree/BinaryTree/Traversal.java

@@ -0,0 +1,49 @@
+package tree.BinaryTree;
+
+public class Traversal {
+    public static void preOrderTravers(Node root) {
+        if (root == null) {
+            System.out.print(-1 + " ");
+            return;
+        }
+
+        System.out.print(root.data + " ");
+        preOrderTravers(root.left);
+        preOrderTravers(root.right);
+    }
+
+    public static void inOrderTravers(Node root) {
+        if (root == null) {
+            System.out.print(-1 + " ");
+            return;
+        }
+
+        inOrderTravers(root.left);
+        System.out.print(root.data + " ");
+        inOrderTravers(root.right);
+    }
+
+    public static void postOrderTravers(Node root) {
+        if (root == null) {
+            System.out.print(-1 + " ");
+            return;
+        }
+
+        postOrderTravers(root.left);
+        postOrderTravers(root.right);
+        System.out.print(root.data + " ");
+    }
+
+    public static void main(String[] args) {
+        int[] nodes = { 9, 2, 4, -1, -1, 5, -1, -1, 3, -1, 6, -1, -1 };
+
+        CreateBT tree = new CreateBT();
+        Node root = tree.createTreeFromArr(nodes);
+
+        preOrderTravers(root);
+        System.out.println();
+        inOrderTravers(root);
+        System.out.println();
+        postOrderTravers(root);
+    }
+}

tree/collectionFramework/TreeS.java

@@ -1,7 +1,5 @@
 package tree.collectionFramework;
-
 import java.util.TreeSet;
-
 public class TreeS {
     public static void main(String[] args) {
         TreeSet<String> set = new TreeSet<String>();
@@ -11,7 +9,7 @@ public static void main(String[] args) {
         set.add("c");
         set.add("d");
         set.add("e");
-
+        
         System.out.println(set);
     }
 }