Perfect Binary Tree Specific Level Order Traversal
Given a Perfect Binary Tree like below:
Print the level order of nodes in following specific manner:
1 2 3 4 7 5 6 8 15 9 14 10 13 11 12 16 31 17 30 18 29 19 28 20 27 21 26 22 25 23 24
i.e. print nodes in level order but nodes should be from left and right side alternatively. Here 1st and 2nd levels are trivial. While 3rd level: 4(left), 7(right), 5(left), 6(right) are printed. While 4th level: 8(left), 15(right), 9(left), 14(right), .. are printed. While 5th level: 16(left), 31(right), 17(left), 30(right), .. are printed.
We strongly recommend to minimize your browser and try this yourself first.
In standard Level Order Traversal, we enqueue root into a queue 1st, then we dequeue ONE node from queue, process (print) it, enqueue its children into queue. We keep doing this until queue is empty.
Approach 1: We can do standard level order traversal here too but instead of printing nodes directly, we have to store nodes in current level in a temporary array or list 1st and then take nodes from alternate ends (left and right) and print nodes. Keep repeating this for all levels.
This approach takes more memory than standard traversal.
C++
// C++ program for special order traversal #include <iostream> #include <queue> using namespace std; // A binary tree node has data, pointer to left child // and a pointer to right child struct Node{ int data; Node *left; Node *right; }; // Helper function that allocates a new node with the // given data and NULL left and right pointers. Node *newNode( int data){ Node *node = new Node; node->data = data; node->right = node->left = NULL; return node; } // Given a perfect binary tree, print its nodes in specific // level order void printSpecificLevelOrder(Node *root){ if (root == NULL) return ; // declare queue for level order traversal queue<Node*> q; q.push(root); vector<Node*> vec; cout<<root->data<< " " ; while (!q.empty()){ int n = q.size(); for ( int i = 0; i<n; i++){ Node* temp = q.front(); q.pop(); if (temp->left != NULL){ q.push(temp->left); vec.push_back(temp->left); } if (temp->right != NULL){ q.push(temp->right); vec.push_back(temp->right); } } auto it1 = vec.begin(); auto it2 = vec.end()-1; while (it1 < it2){ cout<<(*it1)->data<< " " ; cout<<(*it2)->data<< " " ; it1++; it2--; } vec.clear(); } } // Driver program to test above functions int main() { //Perfect Binary Tree of Height 4 Node *root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); root->right->left = newNode(6); root->right->right = newNode(7); root->left->left->left = newNode(8); root->left->left->right = newNode(9); root->left->right->left = newNode(10); root->left->right->right = newNode(11); root->right->left->left = newNode(12); root->right->left->right = newNode(13); root->right->right->left = newNode(14); root->right->right->right = newNode(15); root->left->left->left->left = newNode(16); root->left->left->left->right = newNode(17); root->left->left->right->left = newNode(18); root->left->left->right->right = newNode(19); root->left->right->left->left = newNode(20); root->left->right->left->right = newNode(21); root->left->right->right->left = newNode(22); root->left->right->right->right = newNode(23); root->right->left->left->left = newNode(24); root->right->left->left->right = newNode(25); root->right->left->right->left = newNode(26); root->right->left->right->right = newNode(27); root->right->right->left->left = newNode(28); root->right->right->left->right = newNode(29); root->right->right->right->left = newNode(30); root->right->right->right->right = newNode(31); cout << "Specific Level Order traversal of binary tree is \n" ; printSpecificLevelOrder(root); return 0; } // this code is contributed by Kirti Agarwal(kirtiagarwal23121999) |
Java
// Java program for the above approach import java.util.*; // A binary tree node has data, pointer to left child // and a pointer to right child class Node { int data; Node left, right; // Helper function that allocates a new node with the // given data and NULL left and right pointers. public Node( int data) { this .data = data; this .left = null ; this .right = null ; } } class SpecialOrderTraversal { // Given a perfect binary tree, print its nodes in specific // level order public static void printSpecificLevelOrder(Node root) { if (root == null ) return ; // declare queue for level order traversal Queue<Node> q = new LinkedList<>(); Vector<Node> vec = new Vector<>(); System.out.print(root.data + " " ); q.add(root); while (!q.isEmpty()) { int n = q.size(); for ( int i = 0 ; i < n; i++) { Node temp = q.poll(); if (temp.left != null ) { q.add(temp.left); vec.add(temp.left); } if (temp.right != null ) { q.add(temp.right); vec.add(temp.right); } } int size = vec.size(); for ( int i = 0 ; i < size / 2 ; i++) { System.out.print(vec.get(i).data + " " ); System.out.print(vec.get(size - 1 - i).data + " " ); } if (size % 2 != 0 ) { System.out.print(vec.get(size / 2 ).data + " " ); } vec.clear(); } } // Driver program to test above functions public static void main(String[] args) { // Perfect Binary Tree of Height 4 Node root = new Node( 1 ); root.left = new Node( 2 ); root.right = new Node( 3 ); root.left.left = new Node( 4 ); root.left.right = new Node( 5 ); root.right.left = new Node( 6 ); root.right.right = new Node( 7 ); root.left.left.left = new Node( 8 ); root.left.left.right = new Node( 9 ); root.left.right.left = new Node( 10 ); root.left.right.right = new Node( 11 ); root.right.left.left = new Node( 12 ); root.right.left.right = new Node( 13 ); root.right.right.left = new Node( 14 ); root.right.right.right = new Node( 15 ); root.left.left.left.left = new Node( 16 ); root.left.left.left.right = new Node( 17 ); root.left.left.right.left = new Node( 18 ); root.left.left.right.right = new Node( 19 ); root.left.right.left.left = new Node( 20 ); root.left.right.left.right = new Node( 21 ); root.left.right.right.left = new Node( 22 ); root.left.right.right.right = new Node( 23 ); root.right.left.left.left = new Node( 24 ); root.right.left.left.right = new Node( 25 ); root.right.left.right.left = new Node( 26 ); root.right.left.right.right = new Node( 27 ); root.right.right.left.left = new Node( 28 ); root.right.right.left.right = new Node( 29 ); root.right.right.right.left = new Node( 30 ); root.right.right.right.right = new Node( 31 ); System.out.println( "Specific Level Order traversal of binary tree is:" ); printSpecificLevelOrder(root); } } // This code is contributed by codebraxnzt |
Python3
from queue import Queue # A binary tree node has data, pointer to left child # and a pointer to right child class Node: def __init__( self , data): self .data = data self .left = None self .right = None # Given a perfect binary tree, print its nodes in specific # level order def printSpecificLevelOrder(root): if root is None : return # declare queue for level order traversal q = Queue() vec = [] print (root.data, end = " " ) q.put(root) while not q.empty(): n = q.qsize() for i in range (n): temp = q.get() if temp.left is not None : q.put(temp.left) vec.append(temp.left) if temp.right is not None : q.put(temp.right) vec.append(temp.right) size = len (vec) for i in range (size / / 2 ): print (vec[i].data, end = " " ) print (vec[size - 1 - i].data, end = " " ) if size % 2 ! = 0 : print (vec[size / / 2 ].data, end = " " ) vec.clear() # Driver program to test above functions if __name__ = = '__main__' : # Perfect Binary Tree of Height 4 root = Node( 1 ) root.left = Node( 2 ) root.right = Node( 3 ) root.left.left = Node( 4 ) root.left.right = Node( 5 ) root.right.left = Node( 6 ) root.right.right = Node( 7 ) root.left.left.left = Node( 8 ) root.left.left.right = Node( 9 ) root.left.right.left = Node( 10 ) root.left.right.right = Node( 11 ) root.right.left.left = Node( 12 ) root.right.left.right = Node( 13 ) root.right.right.left = Node( 14 ) root.right.right.right = Node( 15 ) root.left.left.left.left = Node( 16 ) root.left.left.left.right = Node( 17 ) root.left.left.right.left = Node( 18 ) root.left.left.right.right = Node( 19 ) root.left.right.left.left = Node( 20 ) root.left.right.left.right = Node( 21 ) root.left.right.right.left = Node( 22 ) root.left.right.right.right = Node( 23 ) root.right.left.left.left = Node( 24 ) root.right.left.left.right = Node( 25 ) root.right.left.right.left = Node( 26 ) root.right.left.right.right = Node( 27 ) root.right.right.left.left = Node( 28 ) root.right.right.left.right = Node( 29 ) root.right.right.right.left = Node( 30 ) root.right.right.right.right = Node( 31 ) print ( "Specific Level Order traversal of binary tree is:" ) printSpecificLevelOrder(root) |
C#
using System; using System.Collections.Generic; public class Node { public int data; public Node left; public Node right; public Node( int data) { this .data = data; this .left = null ; this .right = null ; } } public class BinaryTree { public Node root; public BinaryTree(Node node) { root = node; } // Given a perfect binary tree, print its nodes in specific level order public void PrintSpecificLevelOrder() { if (root == null ) return ; // declare queue for level order traversal Queue<Node> q = new Queue<Node>(); q.Enqueue(root); List<Node> vec = new List<Node>(); Console.Write(root.data + " " ); while (q.Count != 0) { int n = q.Count; for ( int i = 0; i < n; i++) { Node temp = q.Peek(); q.Dequeue(); if (temp.left != null ) { q.Enqueue(temp.left); vec.Add(temp.left); } if (temp.right != null ) { q.Enqueue(temp.right); vec.Add(temp.right); } } int it1 = 0; int it2 = vec.Count-1; while (it1 < it2) { Console.Write(vec[it1].data + " " ); Console.Write(vec[it2].data + " " ); it1++; it2--; } vec.Clear(); } } static void Main( string [] args) { // Perfect Binary Tree of Height 4 Node root = new Node(1); root.left = new Node(2); root.right = new Node(3); root.left.left = new Node(4); root.left.right = new Node(5); root.right.left = new Node(6); root.right.right = new Node(7); root.left.left.left = new Node(8); root.left.left.right = new Node(9); root.left.right.left = new Node(10); root.left.right.right = new Node(11); root.right.left.left = new Node(12); root.right.left.right = new Node(13); root.right.right.left = new Node(14); root.right.right.right = new Node(15); root.left.left.left.left = new Node(16); root.left.left.left.right = new Node(17); root.left.left.right.left = new Node(18); root.left.left.right.right = new Node(19); root.left.right.left.left = new Node(20); root.left.right.left.right = new Node(21); root.left.right.right.left = new Node(22); root.left.right.right.right = new Node(23); root.right.left.left.left = new Node(24); root.right.left.left.right = new Node(25); root.right.left.right.left = new Node(26); root.right.left.right.right = new Node(27); root.right.right.left.left = new Node(28); root.right.right.left.right = new Node(29); root.right.right.right.left = new Node(30); root.right.right.right.right = new Node(31); BinaryTree tree = new BinaryTree(root); Console.WriteLine( "Specific Level Order traversal of binary tree is:" ); tree.PrintSpecificLevelOrder(); Console.ReadKey(); } } |
Javascript
// THIS CODE IS CONTRIBUTED BY KIRTI AGARWAL(KIRTIAGARWAL23121999) // JavaScript program for special order traversal // A binary tree node has data, pointer to left child // and a pointer to right child class Node{ constructor(data){ this .data = data; this .left = null ; this .right = null ; } } // Helper function that allocates a new node with the // given data and NULL left and right pointers. function newNode(data){ return new Node(data); } // Given a perfect binary tree, print its nodes in specific // level order function printSpecificLevelOrder(root){ if (root == null ) return ; // declare queue for level order traversal let q = []; q.push(root); let vec = []; console.log(root.data + " " ); while (q.length > 0){ let n = q.length; for (let i = 0; i<n; i++){ let temp = q.shift(); if (temp.left != null ){ q.push(temp.left); vec.push(temp.left); } if (temp.right != null ){ q.push(temp.right); vec.push(temp.right); } } let it1 = 0; let it2 = vec.length-1; while (it1 < it2){ console.log(vec[it1].data + " " ) ; console.log(vec[it2].data + " " ) ; it1++; it2--; } vec = []; } } // driver program to test above functions let root = newNode(1); root.left = newNode(2); root.right = newNode(3); root.left.left = newNode(4); root.left.right = newNode(5); root.right.left = newNode(6); root.right.right = newNode(7); root.left.left.left = newNode(8); root.left.left.right = newNode(9); root.left.right.left = newNode(10); root.left.right.right = newNode(11); root.right.left.left = newNode(12); root.right.left.right = newNode(13); root.right.right.left = newNode(14); root.right.right.right = newNode(15); root.left.left.left.left = newNode(16); root.left.left.left.right = newNode(17); root.left.left.right.left = newNode(18); root.left.left.right.right = newNode(19); root.left.right.left.left = newNode(20); root.left.right.left.right = newNode(21); root.left.right.right.left = newNode(22); root.left.right.right.right = newNode(23); root.right.left.left.left = newNode(24); root.right.left.left.right = newNode(25); root.right.left.right.left = newNode(26); root.right.left.right.right = newNode(27); root.right.right.left.left = newNode(28); root.right.right.left.right = newNode(29); root.right.right.right.left = newNode(30); root.right.right.right.right = newNode(31); console.log( "Specific Level Order Traversal of binary tree is : " ); printSpecificLevelOrder(root); |
Specific Level Order traversal of binary tree is 1 2 3 4 7 5 6 8 15 9 14 10 13 11 12 16 31 17 30 18 29 19 28 20 27 21 26 22 25 23 24
Time Complexity: O(N) where N is the number of nodes in given binary tree.
Auxiliary Space: O(N) due to queue and vector data structure.
Approach 2: The standard level order traversal idea will slightly change here. Instead of processing ONE node at a time, we will process TWO nodes at a time. And while pushing children into queue, the enqueue order will be: 1st node’s left child, 2nd node’s right child, 1st node’s right child and 2nd node’s left child.
Implementation:
C++
/* C++ program for special order traversal */ #include <iostream> #include <queue> using namespace std; /* A binary tree node has data, pointer to left child and a pointer to right child */ struct Node { int data; Node *left; Node *right; }; /* Helper function that allocates a new node with the given data and NULL left and right pointers. */ Node *newNode( int data) { Node *node = new Node; node->data = data; node->right = node->left = NULL; return node; } /* Given a perfect binary tree, print its nodes in specific level order */ void printSpecificLevelOrder(Node *root) { if (root == NULL) return ; // Let us print root and next level first cout << root->data; // / Since it is perfect Binary Tree, right is not checked if (root->left != NULL) cout << " " << root->left->data << " " << root->right->data; // Do anything more if there are nodes at next level in // given perfect Binary Tree if (root->left->left == NULL) return ; // Create a queue and enqueue left and right children of root queue <Node *> q; q.push(root->left); q.push(root->right); // We process two nodes at a time, so we need two variables // to store two front items of queue Node *first = NULL, *second = NULL; // traversal loop while (!q.empty()) { // Pop two items from queue first = q.front(); q.pop(); second = q.front(); q.pop(); // Print children of first and second in reverse order cout << " " << first->left->data << " " << second->right->data; cout << " " << first->right->data << " " << second->left->data; // If first and second have grandchildren, enqueue them // in reverse order if (first->left->left != NULL) { q.push(first->left); q.push(second->right); q.push(first->right); q.push(second->left); } } } /* Driver program to test above functions*/ int main() { //Perfect Binary Tree of Height 4 Node *root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); root->right->left = newNode(6); root->right->right = newNode(7); root->left->left->left = newNode(8); root->left->left->right = newNode(9); root->left->right->left = newNode(10); root->left->right->right = newNode(11); root->right->left->left = newNode(12); root->right->left->right = newNode(13); root->right->right->left = newNode(14); root->right->right->right = newNode(15); root->left->left->left->left = newNode(16); root->left->left->left->right = newNode(17); root->left->left->right->left = newNode(18); root->left->left->right->right = newNode(19); root->left->right->left->left = newNode(20); root->left->right->left->right = newNode(21); root->left->right->right->left = newNode(22); root->left->right->right->right = newNode(23); root->right->left->left->left = newNode(24); root->right->left->left->right = newNode(25); root->right->left->right->left = newNode(26); root->right->left->right->right = newNode(27); root->right->right->left->left = newNode(28); root->right->right->left->right = newNode(29); root->right->right->right->left = newNode(30); root->right->right->right->right = newNode(31); cout << "Specific Level Order traversal of binary tree is \n" ; printSpecificLevelOrder(root); return 0; } |
Java
// Java program for special level order traversal import java.util.LinkedList; import java.util.Queue; /* Class containing left and right child of current node and key value*/ class Node { int data; Node left, right; public Node( int item) { data = item; left = right = null ; } } class BinaryTree { Node root; /* Given a perfect binary tree, print its nodes in specific level order */ void printSpecificLevelOrder(Node node) { if (node == null ) return ; // Let us print root and next level first System.out.print(node.data); // Since it is perfect Binary Tree, right is not checked if (node.left != null ) System.out.print( " " + node.left.data + " " + node.right.data); // Do anything more if there are nodes at next level in // given perfect Binary Tree if (node.left.left == null ) return ; // Create a queue and enqueue left and right children of root Queue<Node> q = new LinkedList<Node>(); q.add(node.left); q.add(node.right); // We process two nodes at a time, so we need two variables // to store two front items of queue Node first = null , second = null ; // traversal loop while (!q.isEmpty()) { // Pop two items from queue first = q.peek(); q.remove(); second = q.peek(); q.remove(); // Print children of first and second in reverse order System.out.print( " " + first.left.data + " " +second.right.data); System.out.print( " " + first.right.data + " " +second.left.data); // If first and second have grandchildren, enqueue them // in reverse order if (first.left.left != null ) { q.add(first.left); q.add(second.right); q.add(first.right); q.add(second.left); } } } // Driver program to test for above functions public static void main(String args[]) { BinaryTree tree = new BinaryTree(); tree.root = new Node( 1 ); tree.root.left = new Node( 2 ); tree.root.right = new Node( 3 ); tree.root.left.left = new Node( 4 ); tree.root.left.right = new Node( 5 ); tree.root.right.left = new Node( 6 ); tree.root.right.right = new Node( 7 ); tree.root.left.left.left = new Node( 8 ); tree.root.left.left.right = new Node( 9 ); tree.root.left.right.left = new Node( 10 ); tree.root.left.right.right = new Node( 11 ); tree.root.right.left.left = new Node( 12 ); tree.root.right.left.right = new Node( 13 ); tree.root.right.right.left = new Node( 14 ); tree.root.right.right.right = new Node( 15 ); tree.root.left.left.left.left = new Node( 16 ); tree.root.left.left.left.right = new Node( 17 ); tree.root.left.left.right.left = new Node( 18 ); tree.root.left.left.right.right = new Node( 19 ); tree.root.left.right.left.left = new Node( 20 ); tree.root.left.right.left.right = new Node( 21 ); tree.root.left.right.right.left = new Node( 22 ); tree.root.left.right.right.right = new Node( 23 ); tree.root.right.left.left.left = new Node( 24 ); tree.root.right.left.left.right = new Node( 25 ); tree.root.right.left.right.left = new Node( 26 ); tree.root.right.left.right.right = new Node( 27 ); tree.root.right.right.left.left = new Node( 28 ); tree.root.right.right.left.right = new Node( 29 ); tree.root.right.right.right.left = new Node( 30 ); tree.root.right.right.right.right = new Node( 31 ); System.out.println( "Specific Level Order traversal of binary" + "tree is " ); tree.printSpecificLevelOrder(tree.root); } } // This code has been contributed by Mayank Jaiswal |
Python3
# Python program for special order traversal # A binary tree node class Node: # A constructor for making a new node def __init__( self , key): self .data = key self .left = None self .right = None # Given a perfect binary tree print its node in # specific order def printSpecificLevelOrder(root): if root is None : return # Let us print root and next level first print (root.data,end = " " ) # Since it is perfect Binary tree, # one of the node is needed to be checked if root.left is not None : print (root.left.data,end = " " ) print (root.right.data,end = " " ) # Do anything more if there are nodes at next level # in given perfect Binary Tree if root.left.left is None : return # Create a queue and enqueue left and right # children of root q = [] q.append(root.left) q.append(root.right) # We process two nodes at a time, so we need # two variables to store two front items of queue first = None second = None # Traversal loop while ( len (q) > 0 ): # Pop two items from queue first = q.pop( 0 ) second = q.pop( 0 ) # Print children of first and second in reverse order print (first.left.data,end = " " ) print (second.right.data,end = " " ) print (first.right.data,end = " " ) print (second.left.data,end = " " ) # If first and second have grandchildren, # enqueue them in reverse order if first.left.left is not None : q.append(first.left) q.append(second.right) q.append(first.right) q.append(second.left) # Driver program to test above function # Perfect Binary Tree of Height 4 root = Node( 1 ) root.left = Node( 2 ) root.right = Node( 3 ) root.left.left = Node( 4 ) root.left.right = Node( 5 ) root.right.left = Node( 6 ) root.right.right = Node( 7 ) root.left.left.left = Node( 8 ) root.left.left.right = Node( 9 ) root.left.right.left = Node( 10 ) root.left.right.right = Node( 11 ) root.right.left.left = Node( 12 ) root.right.left.right = Node( 13 ) root.right.right.left = Node( 14 ) root.right.right.right = Node( 15 ) root.left.left.left.left = Node( 16 ) root.left.left.left.right = Node( 17 ) root.left.left.right.left = Node( 18 ) root.left.left.right.right = Node( 19 ) root.left.right.left.left = Node( 20 ) root.left.right.left.right = Node( 21 ) root.left.right.right.left = Node( 22 ) root.left.right.right.right = Node( 23 ) root.right.left.left.left = Node( 24 ) root.right.left.left.right = Node( 25 ) root.right.left.right.left = Node( 26 ) root.right.left.right.right = Node( 27 ) root.right.right.left.left = Node( 28 ) root.right.right.left.right = Node( 29 ) root.right.right.right.left = Node( 30 ) root.right.right.right.right = Node( 31 ) print ( "Specific Level Order traversal of binary tree is" ) printSpecificLevelOrder(root); # This code is contributed by Nikhil Kumar Singh(nickzuck_007) |
C#
// C# program for special level // order traversal using System; using System.Collections.Generic; /* Class containing left and right child of current node and key value*/ public class Node { public int data; public Node left, right; public Node( int item) { data = item; left = right = null ; } } class GFG { public Node root; /* Given a perfect binary tree, print its nodes in specific level order */ public virtual void printSpecificLevelOrder(Node node) { if (node == null ) { return ; } // Let us print root and next level first Console.Write(node.data); // Since it is perfect Binary Tree, // right is not checked if (node.left != null ) { Console.Write( " " + node.left.data + " " + node.right.data); } // Do anything more if there // are nodes at next level in // given perfect Binary Tree if (node.left.left == null ) { return ; } // Create a queue and enqueue left // and right children of root LinkedList<Node> q = new LinkedList<Node>(); q.AddLast(node.left); q.AddLast(node.right); // We process two nodes at a time, // so we need two variables to // store two front items of queue Node first = null , second = null ; // traversal loop while (q.Count > 0) { // Pop two items from queue first = q.First.Value; q.RemoveFirst(); second = q.First.Value; q.RemoveFirst(); // Print children of first and // second in reverse order Console.Write( " " + first.left.data + " " + second.right.data); Console.Write( " " + first.right.data + " " + second.left.data); // If first and second have grandchildren, // enqueue them in reverse order if (first.left.left != null ) { q.AddLast(first.left); q.AddLast(second.right); q.AddLast(first.right); q.AddLast(second.left); } } } // Driver Code public static void Main( string [] args) { GFG tree = new GFG(); tree.root = new Node(1); tree.root.left = new Node(2); tree.root.right = new Node(3); tree.root.left.left = new Node(4); tree.root.left.right = new Node(5); tree.root.right.left = new Node(6); tree.root.right.right = new Node(7); tree.root.left.left.left = new Node(8); tree.root.left.left.right = new Node(9); tree.root.left.right.left = new Node(10); tree.root.left.right.right = new Node(11); tree.root.right.left.left = new Node(12); tree.root.right.left.right = new Node(13); tree.root.right.right.left = new Node(14); tree.root.right.right.right = new Node(15); tree.root.left.left.left.left = new Node(16); tree.root.left.left.left.right = new Node(17); tree.root.left.left.right.left = new Node(18); tree.root.left.left.right.right = new Node(19); tree.root.left.right.left.left = new Node(20); tree.root.left.right.left.right = new Node(21); tree.root.left.right.right.left = new Node(22); tree.root.left.right.right.right = new Node(23); tree.root.right.left.left.left = new Node(24); tree.root.right.left.left.right = new Node(25); tree.root.right.left.right.left = new Node(26); tree.root.right.left.right.right = new Node(27); tree.root.right.right.left.left = new Node(28); tree.root.right.right.left.right = new Node(29); tree.root.right.right.right.left = new Node(30); tree.root.right.right.right.right = new Node(31); Console.WriteLine( "Specific Level Order " + "traversal of binary" + "tree is " ); tree.printSpecificLevelOrder(tree.root); } } // This code is contributed by Shrikant13 |
Javascript
<script> // JavaScript program for special level // order traversal /* Class containing left and right child of current node and key value*/ class Node { constructor(item) { this .data = item; this .left = null ; this .right = null ; } } var root = null ; /* Given a perfect binary tree, print its nodes in specific level order */ function printSpecificLevelOrder(node) { if (node == null ) { return ; } // Let us print root and next level first document.write(node.data); // Since it is perfect Binary Tree, // right is not checked if (node.left != null ) { document.write( " " + node.left.data + " " + node.right.data); } // Do anything more if there // are nodes at next level in // given perfect Binary Tree if (node.left.left == null ) { return ; } // Create a queue and enqueue left // and right children of root var q = []; q.push(node.left); q.push(node.right); // We process two nodes at a time, // so we need two variables to // store two front items of queue var first = null , second = null ; // traversal loop while (q.length > 0) { // Pop two items from queue first = q[0]; q.shift(); second = q[0]; q.shift(); // Print children of first and // second in reverse order document.write( " " + first.left.data + " " + second.right.data); document.write( " " + first.right.data + " " + second.left.data); // If first and second have grandchildren, // enqueue them in reverse order if (first.left.left != null ) { q.push(first.left); q.push(second.right); q.push(first.right); q.push(second.left); } } } // Driver Code root = new Node(1); root.left = new Node(2); root.right = new Node(3); root.left.left = new Node(4); root.left.right = new Node(5); root.right.left = new Node(6); root.right.right = new Node(7); root.left.left.left = new Node(8); root.left.left.right = new Node(9); root.left.right.left = new Node(10); root.left.right.right = new Node(11); root.right.left.left = new Node(12); root.right.left.right = new Node(13); root.right.right.left = new Node(14); root.right.right.right = new Node(15); root.left.left.left.left = new Node(16); root.left.left.left.right = new Node(17); root.left.left.right.left = new Node(18); root.left.left.right.right = new Node(19); root.left.right.left.left = new Node(20); root.left.right.left.right = new Node(21); root.left.right.right.left = new Node(22); root.left.right.right.right = new Node(23); root.right.left.left.left = new Node(24); root.right.left.left.right = new Node(25); root.right.left.right.left = new Node(26); root.right.left.right.right = new Node(27); root.right.right.left.left = new Node(28); root.right.right.left.right = new Node(29); root.right.right.right.left = new Node(30); root.right.right.right.right = new Node(31); document.write( "Specific Level Order " + "traversal of binary" + "tree is <br>" ); printSpecificLevelOrder(root); </script> |
Specific Level Order traversal of binary tree is 1 2 3 4 7 5 6 8 15 9 14 10 13 11 12 16 31 17 30 18 29 19 28 20 27 21 26 22 25 23 24
Time Complexity: O(n) where n is the total number of nodes in the tree.
Auxiliary Space : O(n)
Followup Questions:
- The above code prints specific level order from TOP to BOTTOM. How will you do specific level order traversal from BOTTOM to TOP (Amazon Interview | Set 120 – Round 1 Last Problem)
- What if tree is not perfect, but complete.
- What if tree is neither perfect, nor complete. It can be any general binary tree.
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