# Print all even nodes of Binary Search Tree

Given a binary search tree. The task is to print all even nodes of the binary search tree.

Examples:

```Input :
5
/   \
3     7
/ \   / \
2   4 6   8
Output : 2 4 6 8

Input :
14
/   \
12    17
/ \   / \
8  13 16   19
Output : 8 12 14 16
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: Traverse the Binary Search tree and check if current node’s value is even. If yes then print it otherwise skip that node.

Below is the implementation of the above Approach:

## C++

 `// C++ program to print all even node of BST ` `#include ` `using` `namespace` `std; ` ` `  `// create Tree ` `struct` `Node { ` `    ``int` `key; ` `    ``struct` `Node *left, *right; ` `}; ` ` `  `// A utility function to create a new BST node ` `Node* newNode(``int` `item) ` `{ ` `    ``Node* temp = ``new` `Node; ` `    ``temp->key = item; ` `    ``temp->left = temp->right = NULL; ` `    ``return` `temp; ` `} ` ` `  `// A utility function to do inorder traversal of BST ` `void` `inorder(Node* root) ` `{ ` `    ``if` `(root != NULL) { ` `        ``inorder(root->left); ` `        ``printf``(root->key,end=``" "``); ` `        ``inorder(root->right); ` `    ``} ` `} ` ` `  `/* A utility function to insert a new node ` `   ``with given key in BST */` `Node* insert(Node* node, ``int` `key) ` `{ ` `    ``/* If the tree is empty, return a new node */` `    ``if` `(node == NULL) ` `        ``return` `newNode(key); ` ` `  `    ``/* Otherwise, recur down the tree */` `    ``if` `(key < node->key) ` `        ``node->left = insert(node->left, key); ` `    ``else` `        ``node->right = insert(node->right, key); ` ` `  `    ``/* return the (unchanged) node pointer */` `    ``return` `node; ` `} ` ` `  `// Function to print all even nodes ` `void` `evenNode(Node* root) ` `{ ` `    ``if` `(root != NULL) { ` `        ``evenNode(root->left); ` `        ``// if node is even then print it ` `        ``if` `(root->key % 2 == 0) ` `            ``printf``(``"%d "``, root->key); ` `        ``evenNode(root->right); ` `    ``} ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``/* Let us create following BST  ` `       ``5  ` `      ``/ \  ` `     ``3     7  ` `    ``/ \ / \  ` `    ``2 4 6 8 */` `    ``Node* root = NULL; ` `    ``root = insert(root, 5); ` `    ``root = insert(root, 3); ` `    ``root = insert(root, 2); ` `    ``root = insert(root, 4); ` `    ``root = insert(root, 7); ` `    ``root = insert(root, 6); ` `    ``root = insert(root, 8); ` ` `  `    ``evenNode(root); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to print all even node of BST  ` `class` `GfG {  ` ` `  `// create Tree  ` `static` `class` `Node {  ` `    ``int` `key;  ` `    ``Node left, right;  ` `} ` ` `  `// A utility function to create a new BST node  ` `static` `Node newNode(``int` `item)  ` `{  ` `    ``Node temp = ``new` `Node();  ` `    ``temp.key = item;  ` `    ``temp.left = ``null``; ` `    ``temp.right = ``null``;  ` `    ``return` `temp;  ` `}  ` ` `  `// A utility function to do inorder traversal of BST  ` `static` `void` `inorder(Node root)  ` `{  ` `    ``if` `(root != ``null``) {  ` `        ``inorder(root.left);  ` `        ``System.out.print(root.key + ``" "``);  ` `        ``inorder(root.right);  ` `    ``}  ` `}  ` ` `  `/* A utility function to insert a new node  ` `with given key in BST */` `static` `Node insert(Node node, ``int` `key)  ` `{  ` `    ``/* If the tree is empty, return a new node */` `    ``if` `(node == ``null``)  ` `        ``return` `newNode(key);  ` ` `  `    ``/* Otherwise, recur down the tree */` `    ``if` `(key < node.key)  ` `        ``node.left = insert(node.left, key);  ` `    ``else` `        ``node.right = insert(node.right, key);  ` ` `  `    ``/* return the (unchanged) node pointer */` `    ``return` `node;  ` `}  ` ` `  `// Function to print all even nodes  ` `static` `void` `evenNode(Node root)  ` `{  ` `    ``if` `(root != ``null``) {  ` `        ``evenNode(root.left);  ` `        ``// if node is even then print it  ` `        ``if` `(root.key % ``2` `== ``0``)  ` `            ``System.out.print(root.key + ``" "``);  ` `        ``evenNode(root.right);  ` `    ``}  ` `}  ` ` `  `// Driver Code  ` `public` `static` `void` `main(String[] args)  ` `{  ` `    ``/* Let us create following BST  ` `    ``5  ` `    ``/ \  ` `    ``3     7  ` `    ``/ \ / \  ` `    ``2 4 6 8 */` `    ``Node root = ``null``;  ` `    ``root = insert(root, ``5``);  ` `    ``root = insert(root, ``3``);  ` `    ``root = insert(root, ``2``);  ` `    ``root = insert(root, ``4``);  ` `    ``root = insert(root, ``7``);  ` `    ``root = insert(root, ``6``);  ` `    ``root = insert(root, ``8``);  ` ` `  `    ``evenNode(root);  ` ` `  `} ` `}  `

## Python3

 `# Python3 program to print all even node of BST  ` ` `  `# create Tree  ` `# to create a new BST node  ` `class` `newNode:  ` ` `  `    ``# Construct to create a new node  ` `    ``def` `__init__(``self``, key):  ` `        ``self``.key ``=` `key ` `        ``self``.left ``=` `None` `        ``self``.right ``=` `None` ` `  `# A utility function to do inorder  ` `# traversal of BST  ` `def` `inorder(root) : ` ` `  `    ``if` `(root !``=` `None``):  ` `        ``inorder(root.left)  ` `        ``printf(``"%d "``, root.key)  ` `        ``inorder(root.right)  ` `     `  `""" A utility function to insert a new  ` `node with given key in BST """` `def` `insert(node, key):  ` ` `  `    ``""" If the tree is empty, ` `    ``return a new node """` `    ``if` `(node ``=``=` `None``):  ` `        ``return` `newNode(key)  ` ` `  `    ``""" Otherwise, recur down the tree """` `    ``if` `(key < node.key):  ` `        ``node.left ``=` `insert(node.left, key)  ` `    ``else``: ` `        ``node.right ``=` `insert(node.right, key)  ` ` `  `    ``""" return the (unchanged)  ` `        ``node pointer """` `    ``return` `node  ` ` `  `# Function to print all even nodes  ` `def` `evenNode(root) : ` ` `  `    ``if` `(root !``=` `None``):  ` `        ``evenNode(root.left)  ` `         `  `        ``# if node is even then print it  ` `        ``if` `(root.key ``%` `2` `=``=` `0``): ` `            ``print``(root.key, end ``=` `" "``)  ` `        ``evenNode(root.right)  ` ` `  `# Driver Code  ` `if` `__name__ ``=``=` `'__main__'``: ` `     `  `    ``""" Let us create following BST  ` `    ``5  ` `    ``/ \  ` `    ``3 7  ` `    ``/ \ / \  ` `    ``2 4 6 8 """` `    ``root ``=` `None` `    ``root ``=` `insert(root, ``5``)  ` `    ``root ``=` `insert(root, ``3``)  ` `    ``root ``=` `insert(root, ``2``)  ` `    ``root ``=` `insert(root, ``4``)  ` `    ``root ``=` `insert(root, ``7``)  ` `    ``root ``=` `insert(root, ``6``)  ` `    ``root ``=` `insert(root, ``8``)  ` ` `  `    ``evenNode(root)  ` ` `  `# This code is contributed by ` `# Shubham Singh(SHUBHAMSINGH10) `

## C#

 `// C# program to print all even node of BST  ` `using` `System; ` ` `  `class` `GfG  ` `{  ` ` `  `    ``// create Tree  ` `    ``class` `Node  ` `    ``{  ` `        ``public` `int` `key;  ` `        ``public` `Node left, right;  ` `    ``}  ` ` `  `    ``// A utility function to  ` `    ``// create a new BST node  ` `    ``static` `Node newNode(``int` `item)  ` `    ``{  ` `        ``Node temp = ``new` `Node();  ` `        ``temp.key = item;  ` `        ``temp.left = ``null``;  ` `        ``temp.right = ``null``;  ` `        ``return` `temp;  ` `    ``}  ` ` `  `    ``// A utility function to do ` `    ``// inorder traversal of BST  ` `    ``static` `void` `inorder(Node root)  ` `    ``{  ` `        ``if` `(root != ``null``)  ` `        ``{  ` `            ``inorder(root.left);  ` `            ``Console.Write(root.key + ``" "``);  ` `            ``inorder(root.right);  ` `        ``}  ` `    ``}  ` ` `  `    ``/* A utility function to insert a new node  ` `    ``with given key in BST */` `    ``static` `Node insert(Node node, ``int` `key)  ` `    ``{  ` `        ``/* If the tree is empty, return a new node */` `        ``if` `(node == ``null``)  ` `            ``return` `newNode(key);  ` ` `  `        ``/* Otherwise, recur down the tree */` `        ``if` `(key < node.key)  ` `            ``node.left = insert(node.left, key);  ` `        ``else` `            ``node.right = insert(node.right, key);  ` ` `  `        ``/* return the (unchanged) node pointer */` `        ``return` `node;  ` `    ``}  ` ` `  `    ``// Function to print all even nodes  ` `    ``static` `void` `evenNode(Node root)  ` `    ``{  ` `        ``if` `(root != ``null``) ` `        ``{  ` `            ``evenNode(root.left);  ` `             `  `            ``// if node is even then print it  ` `            ``if` `(root.key % 2 == 0)  ` `                ``Console.Write(root.key + ``" "``);  ` `            ``evenNode(root.right);  ` `        ``}  ` `    ``}  ` ` `  `    ``// Driver Code  ` `    ``public` `static` `void` `Main(String[] args)  ` `    ``{  ` `        ``/* Let us create following BST  ` `        ``5  ` `        ``/ \  ` `        ``3 7  ` `        ``/ \ / \  ` `        ``2 4 6 8 */` `        ``Node root = ``null``;  ` `        ``root = insert(root, 5);  ` `        ``root = insert(root, 3);  ` `        ``root = insert(root, 2);  ` `        ``root = insert(root, 4);  ` `        ``root = insert(root, 7);  ` `        ``root = insert(root, 6);  ` `        ``root = insert(root, 8);  ` ` `  `        ``evenNode(root);  ` `    ``}  ` `}  ` ` `  `// This code has been contributed  ` `// by PrinciRaj1992 `

Output:

```2 4 6 8
```

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