Day-14-BST level order tree traversal(Iterative + recursive)

Author: mandliya

Diff for: tree_problems/levelOrderTraversalIterative.cpp

@@ -0,0 +1,98 @@
+/*
+ * Program to implement level order traversal - iterative version
+ */
+#include <iostream>
+#include <queue.h>
+
+
+const int maxNodes = 15;
+
+struct Node
+{
+    int data;
+    Node* left;
+    Node* right;
+};
+
+/*
+ * An helper function to get a new node
+ */
+
+Node* newNode( int data )
+{
+    Node *temp = new Node;
+    temp->data = data;
+    temp->left = temp->right = nullptr;
+    return temp;
+}
+
+/*
+ * function to insert a new node.
+ * Arg : root Node, new data
+ */
+
+void insert( Node* & node, int data)
+{
+    if ( node == nullptr) 
+    {
+        node = newNode(data);
+    } 
+    else
+    {
+        if (data < node->data) 
+        {
+            insert( node->left, data);
+        }
+        else
+        {
+            insert( node->right, data);
+        }
+    }
+}
+
+/*
+ * Level order traversal
+ */
+void levelOrder( Node * node )
+{
+    std::cout << "Printing level order traversal of the tree:\n";
+    if ( node == nullptr )
+    {
+        std::cout << "Empty tree\n";
+        return ;
+    }
+
+    algo::Queue<Node*> Q(maxNodes);
+    Q.push(node);
+    while ( !Q.empty() )
+    {
+        Node *currNode = Q.front();
+        std::cout << currNode->data << " ";
+        Q.pop();
+        if (currNode->left != nullptr)
+        {
+            Q.push(currNode->left);
+        }
+        if (currNode->right != nullptr)
+        {
+            Q.push(currNode->right);
+        }
+    }
+    std::cout << std::endl;
+}
+
+
+int main()
+{
+    Node * root;
+    insert(root, 4);
+    insert(root, 2);
+    insert(root, 6);
+    insert(root, 1);
+    insert(root, 3);
+    insert(root, 5);
+    insert(root, 7);
+    levelOrder(root);
+    return 0;
+
+}

Diff for: tree_problems/levelOrderTraversalRecursive.cpp

@@ -0,0 +1,96 @@
+/*
+ * Level order BST traveral iterative
+ */
+#include <iostream>
+
+struct Node
+{
+    int data;
+    Node *left;
+    Node *right;
+};
+
+Node* newNode( int data )
+{   
+    Node *temp = new Node;
+    temp->data = data;
+    temp->left = temp->right = nullptr;
+    return temp;
+}
+
+void insert( Node* & node, int data)
+{
+    if ( node == nullptr)
+    {
+        node = newNode(data);
+    }
+    else
+    {
+        if ( data < node->data )
+        {
+            insert(node->left, data);
+        } 
+        else
+        {
+            insert(node->right, data);
+        }
+    }
+}
+
+int height( const Node * node) 
+{
+    if ( node == nullptr )
+    {
+        return 0;
+    }
+    else
+    {
+        int leftHeight = height(node->left);
+        int rightHeight = height(node->right);
+        return ( 1  + ((leftHeight > rightHeight) ? leftHeight : rightHeight));
+    }
+}
+
+void printLevel(Node *node, int level)
+{
+    if (node == nullptr)
+    {
+        return;
+    }
+    if ( level == 1 )
+    {
+        std::cout << node->data <<" ";
+    } 
+    else
+    {
+        printLevel( node->left, level - 1);
+        printLevel( node->right, level - 1);
+    }
+
+}
+
+
+void levelOrder( Node * node )
+{
+    std::cout << "Level order traversal of the tree:\n";
+    int h = height(node);
+    for ( int i = 1; i <= h; ++i ) {
+        printLevel(node, i );
+        std::cout << std::endl;
+    }
+}
+
+int main()
+{
+    Node * root;
+    insert(root, 4);
+    insert(root, 2);
+    insert(root, 6);
+    insert(root, 1);
+    insert(root, 3);
+    insert(root, 5);
+    insert(root, 7);
+    levelOrder(root);
+    return 0;
+}
+