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# Tree Traversal Techniques – Data Structure and Algorithm Tutorials

Unlike linear data structures (Array, Linked List, Queues, Stacks, etc) which have only one logical way to traverse them, trees can be traversed in different ways.

A Tree Data Structure can be traversed in following ways:

1. Depth First Search or DFS
1. Inorder Traversal
2. Preorder Traversal
3. Postorder Traversal
2. Level Order Traversal or Breadth First Search or BFS
3. Boundary Traversal
4. Diagonal Traversal

Tree Traversal

## Inorder Traversal:

Algorithm Inorder(tree)

1. Traverse the left subtree, i.e., call Inorder(left->subtree)
2. Visit the root.
3. Traverse the right subtree, i.e., call Inorder(right->subtree)

### Uses of Inorder Traversal:

In the case of binary search trees (BST), Inorder traversal gives nodes in non-decreasing order. To get nodes of BST in non-increasing order, a variation of Inorder traversal where Inorder traversal is reversed can be used.

Code implementation of Inorder traversal.

## C

 `// C program for different tree traversals``#include ``#include ` `// A binary tree node has data, pointer to left child``// and a pointer to right child``struct` `node {``    ``int` `data;``    ``struct` `node* left;``    ``struct` `node* right;``};` `// Helper function that allocates a new node with the``// given data and NULL left and right pointers.``struct` `node* newNode(``int` `data)``{``    ``struct` `node* node``        ``= (``struct` `node*)``malloc``(``sizeof``(``struct` `node));``    ``node->data = data;``    ``node->left = NULL;``    ``node->right = NULL;` `    ``return` `(node);``}` `// Given a binary tree, print its nodes in inorder``void` `printInorder(``struct` `node* node)``{``    ``if` `(node == NULL)``        ``return``;` `    ``// First recur on left child``    ``printInorder(node->left);` `    ``// Then print the data of node``    ``printf``(``"%d "``, node->data);` `    ``// Now recur on right child``    ``printInorder(node->right);``}` `// Driver code``int` `main()``{``    ``struct` `node* root = newNode(1);``    ``root->left = newNode(2);``    ``root->right = newNode(3);``    ``root->left->left = newNode(4);``    ``root->left->right = newNode(5);` `    ``// Function call``    ``printf``(``"Inorder traversal of binary tree is \n"``);``    ``printInorder(root);` `    ``getchar``();``    ``return` `0;``}`

## C++

 `// C++ program for different tree traversals``#include ``using` `namespace` `std;` `// A binary tree node has data, pointer to left child``// and a pointer to right child``struct` `Node {``    ``int` `data;``    ``struct` `Node *left, *right;``};` `// Utility function to create a new tree node``Node* newNode(``int` `data)``{``    ``Node* temp = ``new` `Node;``    ``temp->data = data;``    ``temp->left = temp->right = NULL;``    ``return` `temp;``}` `// Given a binary tree, print its nodes in inorder``void` `printInorder(``struct` `Node* node)``{``    ``if` `(node == NULL)``        ``return``;` `    ``// First recur on left child``    ``printInorder(node->left);` `    ``// Then print the data of node``    ``cout << node->data << ``" "``;` `    ``// Now recur on right child``    ``printInorder(node->right);``}` `// Driver code``int` `main()``{``    ``struct` `Node* root = newNode(1);``    ``root->left = newNode(2);``    ``root->right = newNode(3);``    ``root->left->left = newNode(4);``    ``root->left->right = newNode(5);` `    ``// Function call``    ``cout << ``"Inorder traversal of binary tree is \n"``;``    ``printInorder(root);` `    ``return` `0;``}`

## Java

 `// Java program for different tree traversals` `// Class containing left and right child of current``// node and key value``class` `Node {``    ``int` `key;``    ``Node left, right;` `    ``public` `Node(``int` `item)``    ``{``        ``key = item;``        ``left = right = ``null``;``    ``}``}` `class` `BinaryTree {` `    ``// Root of Binary Tree``    ``Node root;` `    ``BinaryTree() { root = ``null``; }` `    ``// Given a binary tree, print its nodes in inorder``    ``void` `printInorder(Node node)``    ``{``        ``if` `(node == ``null``)``            ``return``;` `        ``// First recur on left child``        ``printInorder(node.left);` `        ``// Then print the data of node``        ``System.out.print(node.key + ``" "``);` `        ``// Now recur on right child``        ``printInorder(node.right);``    ``}` `    ``// Driver code``    ``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``);` `        ``// Function call``        ``System.out.println(``            ``"Inorder traversal of binary tree is "``);``        ``tree.printInorder(tree.root);``    ``}``}`

## Python3

 `# Python3 program to for tree traversals`  `# A class that represents an individual node in a``# Binary Tree``class` `Node:``    ``def` `__init__(``self``, key):``        ``self``.left ``=` `None``        ``self``.right ``=` `None``        ``self``.val ``=` `key`  `# A function to do inorder tree traversal``def` `printInorder(root):` `    ``if` `root:` `        ``# First recur on left child``        ``printInorder(root.left)` `        ``# Then print the data of node``        ``print``(root.val, end``=``" "``),` `        ``# Now recur on right child``        ``printInorder(root.right)`  `# Driver code``if` `__name__ ``=``=` `"__main__"``:``    ``root ``=` `Node(``1``)``    ``root.left ``=` `Node(``2``)``    ``root.right ``=` `Node(``3``)``    ``root.left.left ``=` `Node(``4``)``    ``root.left.right ``=` `Node(``5``)` `    ``# Function call``    ``print``(``"Inorder traversal of binary tree is"``)``    ``printInorder(root)`

## C#

 `// C# program for different``// tree traversals``using` `System;` `// Class containing left and right child of``// current node and key value``class` `Node {``    ``public` `int` `key;``    ``public` `Node left, right;` `    ``public` `Node(``int` `item)``    ``{``        ``key = item;``        ``left = right = ``null``;``    ``}``}` `class` `BinaryTree {` `    ``// Root of Binary Tree``    ``Node root;` `    ``BinaryTree() { root = ``null``; }` `    ``// Given a binary tree, print``    ``// its nodes in inorder``    ``void` `printInorder(Node node)``    ``{``        ``if` `(node == ``null``)``            ``return``;` `        ``// First recur on left child``        ``printInorder(node.left);` `        ``// Then print the data of node``        ``Console.Write(node.key + ``" "``);` `        ``// Now recur on right child``        ``printInorder(node.right);``    ``}` `    ``// Wrappers over above recursive functions``    ``void` `printInorder() { printInorder(root); }` `    ``// Driver Code``    ``static` `public` `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);` `        ``// Function call``        ``Console.WriteLine(``"Inorder traversal "``                          ``+ ``"of binary tree is "``);``        ``tree.printInorder();``    ``}``}` `// This code is contributed by Arnab Kundu`

## Javascript

 `// javascript program for different tree traversals` `// Class containing left and right child of current``// node and key value``class Node {``    ``constructor(val) {``        ``this``.key = val;``        ``this``.left = ``null``;``        ``this``.right = ``null``;``    ``}``}` `// Root of Binary Tree``var` `root = ``null``;``    ` `// Given a binary tree, print its nodes in inorder``function` `printInorder(node) {``    ``if` `(node == ``null``)``        ``return``;` `    ``// First recur on left child */``    ``printInorder(node.left);` `    ``// Then print the data of node``    ``console.log(node.key + ``" "``);` `    ``// Now recur on right child``    ``printInorder(node.right);``}` `// Driver method``    ` `    ``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);` `    ``console.log(``"Inorder traversal of binary tree is "``);``    ``printInorder(root);` `// This code is contributed by aashish1995`

Output

```Inorder traversal of binary tree is
4 2 5 1 3 ```

Time Complexity: O(N)
Auxiliary Space: If we don’t consider the size of the stack for function calls then O(1) otherwise O(h) where h is the height of the tree.

## Preorder Traversal:

Algorithm Preorder(tree)

1. Visit the root.
2. Traverse the left subtree, i.e., call Preorder(left->subtree)
3. Traverse the right subtree, i.e., call Preorder(right->subtree)

### Uses of Preorder:

Preorder traversal is used to create a copy of the tree. Preorder traversal is also used to get prefix expressions on an expression tree.

Code implementation of Preorder traversal:

## C

 `// C program for different tree traversals``#include ``#include ` `// A binary tree node has data, pointer to left child``// and a pointer to right child``struct` `node {``    ``int` `data;``    ``struct` `node* left;``    ``struct` `node* right;``};` `// Helper function that allocates a new node with the``// given data and NULL left and right pointers.``struct` `node* newNode(``int` `data)``{``    ``struct` `node* node``        ``= (``struct` `node*)``malloc``(``sizeof``(``struct` `node));``    ``node->data = data;``    ``node->left = NULL;``    ``node->right = NULL;` `    ``return` `(node);``}` `// Given a binary tree, print its nodes in preorder``void` `printPreorder(``struct` `node* node)``{``    ``if` `(node == NULL)``        ``return``;` `    ``// First print data of node``    ``printf``(``"%d "``, node->data);` `    ``// Then recur on left subtree``    ``printPreorder(node->left);` `    ``// Now recur on right subtree``    ``printPreorder(node->right);``}` `// Driver code``int` `main()``{``    ``struct` `node* root = newNode(1);``    ``root->left = newNode(2);``    ``root->right = newNode(3);``    ``root->left->left = newNode(4);``    ``root->left->right = newNode(5);` `    ``// Function call``    ``printf``(``"Preorder traversal of binary tree is \n"``);``    ``printPreorder(root);` `    ``getchar``();``    ``return` `0;``}`

## C++

 `// C++ program for different tree traversals``#include ``using` `namespace` `std;` `// A binary tree node has data, pointer to left child``// and a pointer to right child``struct` `Node {``    ``int` `data;``    ``struct` `Node *left, *right;``};` `// Utility function to create a new tree node``Node* newNode(``int` `data)``{``    ``Node* temp = ``new` `Node;``    ``temp->data = data;``    ``temp->left = temp->right = NULL;``    ``return` `temp;``}` `// Given a binary tree, print its nodes in preorder``void` `printPreorder(``struct` `Node* node)``{``    ``if` `(node == NULL)``        ``return``;` `    ``// First print data of node``    ``cout << node->data << ``" "``;` `    ``// Then recur on left subtree``    ``printPreorder(node->left);` `    ``// Now recur on right subtree``    ``printPreorder(node->right);``}` `// Driver code``int` `main()``{``    ``struct` `Node* root = newNode(1);``    ``root->left = newNode(2);``    ``root->right = newNode(3);``    ``root->left->left = newNode(4);``    ``root->left->right = newNode(5);` `    ``// Function call``    ``cout << ``"Preorder traversal of binary tree is \n"``;``    ``printPreorder(root);` `    ``return` `0;``}`

## Java

 `// Java program for different tree traversals` `// Class containing left and right child of current``// node and key value``class` `Node {``    ``int` `key;``    ``Node left, right;` `    ``public` `Node(``int` `item)``    ``{``        ``key = item;``        ``left = right = ``null``;``    ``}``}` `class` `BinaryTree {` `    ``// Root of Binary Tree``    ``Node root;` `    ``BinaryTree() { root = ``null``; }` `    ``// Given a binary tree, print its nodes in preorder``    ``void` `printPreorder(Node node)``    ``{``        ``if` `(node == ``null``)``            ``return``;` `        ``// First print data of node``        ``System.out.print(node.key + ``" "``);` `        ``// Then recur on left subtree``        ``printPreorder(node.left);` `        ``// Now recur on right subtree``        ``printPreorder(node.right);``    ``}` `    ``// Driver code``    ``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``);` `        ``// Function call``        ``System.out.println(``            ``"Preorder traversal of binary tree is "``);``        ``tree.printPreorder(tree.root);``    ``}``}`

## Python3

 `# Python3 program to for tree traversals`  `# A class that represents an individual node``# in a Binary Tree``class` `Node:``    ``def` `__init__(``self``, key):``        ``self``.left ``=` `None``        ``self``.right ``=` `None``        ``self``.val ``=` `key`  `# A function to do preorder tree traversal``def` `printPreorder(root):` `    ``if` `root:` `        ``# First print the data of node``        ``print``(root.val, end``=``" "``),` `        ``# Then recur on left child``        ``printPreorder(root.left)` `        ``# Finally recur on right child``        ``printPreorder(root.right)`  `# Driver code``if` `__name__ ``=``=` `"__main__"``:``    ``root ``=` `Node(``1``)``    ``root.left ``=` `Node(``2``)``    ``root.right ``=` `Node(``3``)``    ``root.left.left ``=` `Node(``4``)``    ``root.left.right ``=` `Node(``5``)` `    ``# Function call``    ``print``(``"Preorder traversal of binary tree is"``)``    ``printPreorder(root)`

## C#

 `// C# program for different``// tree traversals``using` `System;` `// Class containing left and right child of``// current node and key value``class` `Node {``    ``public` `int` `key;``    ``public` `Node left, right;` `    ``public` `Node(``int` `item)``    ``{``        ``key = item;``        ``left = right = ``null``;``    ``}``}` `class` `BinaryTree {` `    ``// Root of Binary Tree``    ``Node root;` `    ``BinaryTree() { root = ``null``; }` `    ``// Given a binary tree, print``    ``// its nodes in preorder``    ``void` `printPreorder(Node node)``    ``{``        ``if` `(node == ``null``)``            ``return``;` `        ``// First print data of node``        ``Console.Write(node.key + ``" "``);` `        ``// Then recur on left subtree``        ``printPreorder(node.left);` `        ``// Now recur on right subtree``        ``printPreorder(node.right);``    ``}` `    ``// Driver Code``    ``static` `public` `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);` `        ``// Function call``        ``Console.WriteLine(``"Preorder traversal "``                          ``+ ``"of binary tree is "``);``        ``tree.printPreorder(tree.root);``    ``}``}` `// This code is contributed by Arnab Kundu`

## Javascript

 `// javascript program for different tree traversals` `// Class containing left and right child of current``// node and key value``class Node {``    ``constructor(val) {``        ``this``.key = val;``        ``this``.left = ``null``;``        ``this``.right = ``null``;``    ``}``}` `// Root of Binary Tree``var` `root = ``null``;` `// Given a binary tree, print its nodes in preorder``function` `printPreorder(node) {``    ``if` `(node == ``null``)``        ``return``;` `    ``// First print data of node``    ``document.write(node.key + ``" "``);` `    ``// Then recur on left subtree``    ``printPreorder(node.left);` `    ``// Now recur on right subtree``    ``printPreorder(node.right);``}` `// Driver method  ``    ` `    ``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);` `    ``console.log(``"Preorder traversal of binary tree is "``);``    ``printPreorder(root);` `// This code is contributed by aashish1995`

Output

```Preorder traversal of binary tree is
1 2 4 5 3 ```

Time Complexity: O(N)
Auxiliary Space: If we don’t consider the size of the stack for function calls then O(1) otherwise O(h) where h is the height of the tree.

## Postorder Traversal:

Algorithm Postorder(tree)

1. Traverse the left subtree, i.e., call Postorder(left->subtree)
2. Traverse the right subtree, i.e., call Postorder(right->subtree)
3. Visit the root

### Uses of Postorder:

Postorder traversal is used to delete the tree. Please see the question for the deletion of a tree for details. Postorder traversal is also useful to get the postfix expression of an expression tree

Below is the implementation of the above traversal methods:

## C

 `// C program for different tree traversals``#include ``#include ` `// A binary tree node has data, pointer to left child``// and a pointer to right child``struct` `node {``    ``int` `data;``    ``struct` `node* left;``    ``struct` `node* right;``};` `// Helper function that allocates a new node with the``// given data and NULL left and right pointers.``struct` `node* newNode(``int` `data)``{``    ``struct` `node* node``        ``= (``struct` `node*)``malloc``(``sizeof``(``struct` `node));``    ``node->data = data;``    ``node->left = NULL;``    ``node->right = NULL;` `    ``return` `(node);``}` `// Given a binary tree, print its nodes according to the``// "bottom-up" postorder traversal.``void` `printPostorder(``struct` `node* node)``{``    ``if` `(node == NULL)``        ``return``;` `    ``// First recur on left subtree``    ``printPostorder(node->left);` `    ``// Then recur on right subtree``    ``printPostorder(node->right);` `    ``// Now deal with the node``    ``printf``(``"%d "``, node->data);``}` `// Driver code``int` `main()``{``    ``struct` `node* root = newNode(1);``    ``root->left = newNode(2);``    ``root->right = newNode(3);``    ``root->left->left = newNode(4);``    ``root->left->right = newNode(5);` `    ``// Function call``    ``printf``(``"Postorder traversal of binary tree is \n"``);``    ``printPostorder(root);` `    ``getchar``();``    ``return` `0;``}`

## C++

 `// C++ program for different tree traversals``#include ``using` `namespace` `std;` `// A binary tree node has data, pointer to left child``// and a pointer to right child``struct` `Node {``    ``int` `data;``    ``struct` `Node *left, *right;``};` `// Utility function to create a new tree node``Node* newNode(``int` `data)``{``    ``Node* temp = ``new` `Node;``    ``temp->data = data;``    ``temp->left = temp->right = NULL;``    ``return` `temp;``}` `// Given a binary tree, print its nodes according to the``// "bottom-up" postorder traversal.``void` `printPostorder(``struct` `Node* node)``{``    ``if` `(node == NULL)``        ``return``;` `    ``// First recur on left subtree``    ``printPostorder(node->left);` `    ``// Then recur on right subtree``    ``printPostorder(node->right);` `    ``// Now deal with the node``    ``cout << node->data << ``" "``;``}` `// Driver code``int` `main()``{``    ``struct` `Node* root = newNode(1);``    ``root->left = newNode(2);``    ``root->right = newNode(3);``    ``root->left->left = newNode(4);``    ``root->left->right = newNode(5);` `    ``// Function call``    ``cout << ``"Postorder traversal of binary tree is \n"``;``    ``printPostorder(root);` `    ``return` `0;``}`

## Java

 `// Java program for different tree traversals` `// Class containing left and right child of current``// node and key value``class` `Node {``    ``int` `key;``    ``Node left, right;` `    ``public` `Node(``int` `item)``    ``{``        ``key = item;``        ``left = right = ``null``;``    ``}``}` `class` `BinaryTree {` `    ``// Root of Binary Tree``    ``Node root;` `    ``BinaryTree() { root = ``null``; }` `    ``// Given a binary tree, print its nodes according to the``    ``// "bottom-up" postorder traversal.``    ``void` `printPostorder(Node node)``    ``{``        ``if` `(node == ``null``)``            ``return``;` `        ``// First recur on left subtree``        ``printPostorder(node.left);` `        ``// Then recur on right subtree``        ``printPostorder(node.right);` `        ``// Now deal with the node``        ``System.out.print(node.key + ``" "``);``    ``}` `    ``// Driver code``    ``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``);` `        ``// Function call``        ``System.out.println(``            ``"Postorder traversal of binary tree is "``);``        ``tree.printPostorder(tree.root);``    ``}``}`

## Python3

 `# Python3 program to for tree traversals`  `# A class that represents an individual node``# in a Binary Tree``class` `Node:``    ``def` `__init__(``self``, key):``        ``self``.left ``=` `None``        ``self``.right ``=` `None``        ``self``.val ``=` `key`  `# A function to do postorder tree traversal``def` `printPostorder(root):` `    ``if` `root:` `        ``# First recur on left child``        ``printPostorder(root.left)` `        ``# The recur on right child``        ``printPostorder(root.right)` `        ``# Now print the data of node``        ``print``(root.val, end``=``" "``),`  `# Driver code``if` `__name__ ``=``=` `"__main__"``:``    ``root ``=` `Node(``1``)``    ``root.left ``=` `Node(``2``)``    ``root.right ``=` `Node(``3``)``    ``root.left.left ``=` `Node(``4``)``    ``root.left.right ``=` `Node(``5``)` `    ``# Function call``    ``print``(``"Postorder traversal of binary tree is"``)``    ``printPostorder(root)`

## C#

 `// C# program for different``// tree traversals``using` `System;` `// Class containing left and right child``// of current node and key value``class` `Node {``    ``public` `int` `key;``    ``public` `Node left, right;` `    ``public` `Node(``int` `item)``    ``{``        ``key = item;``        ``left = right = ``null``;``    ``}``}` `class` `BinaryTree {``    ``// Root of Binary Tree``    ``Node root;` `    ``BinaryTree() { root = ``null``; }` `    ``// Given a binary tree, print its nodes according to``    ``// the "bottom-up" postorder traversal.``    ``void` `printPostorder(Node node)``    ``{``        ``if` `(node == ``null``)``            ``return``;` `        ``// First recur on left subtree``        ``printPostorder(node.left);` `        ``// Then recur on right subtree``        ``printPostorder(node.right);` `        ``// Now deal with the node``        ``Console.Write(node.key + ``" "``);``    ``}` `    ``// Driver Code``    ``static` `public` `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);` `        ``// Function call``        ``Console.WriteLine(``"Postorder traversal "``                          ``+ ``"of binary tree is "``);``        ``tree.printPostorder(tree.root);``    ``}``}` `// This code is contributed by Arnab Kundu`

## Javascript

 `// javascript program for different tree traversals` `// Class containing left and right child of current``// node and key value``class Node {``    ``constructor(val) {``        ``this``.key = val;``        ``this``.left = ``null``;``        ``this``.right = ``null``;``    ``}``}` `// Root of Binary Tree``var` `root = ``null``;``    ` `// Given a binary tree, print its nodes according``// to the "bottom-up" postorder traversal``function` `printPostorder(node) {``    ``if` `(node == ``null``)``        ``return``;` `    ``// First recur on left subtree``    ``printPostorder(node.left);` `    ``// Then recur on right subtree``    ``printPostorder(node.right);` `    ``// Now deal with the node``    ``console.log(node.key + ``" "``);``}` `// Driver method``    ` `    ``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);` `    ``console.log(``"Postorder traversal of binary tree is "``);``    ``printPostorder(root);` `// This code is contributed by aashish1995`

Output

```Postorder traversal of binary tree is
4 5 2 3 1 ```

## Some other Tree Traversals Techniques:

Some of the other tree traversals are:

## Level Order Treversal

For each node, first, the node is visited and then it’s child nodes are put in a FIFO queue. Then again the first node is popped out and then it’s child nodes are put in a FIFO queue and repeat until queue becomes empty.

Example:

Input:

Level Order Treversal:
1
2 3
4 5

## Boundary Traversal

The Boundary Traversal of a Tree includes:

1. left boundary (nodes on left excluding leaf nodes)
2. leaves (consist of only the leaf nodes)
3. right boundary (nodes on right excluding leaf nodes)

## Diagonal Traversal

In the Diagonal Traversal of a Tree, all the nodes in a single diagonal will be printed one by one.

Input

Diagonal Traversal of binary tree:

8 10 14

3 6 7 13

1 4