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Remove all leaf nodes from the binary search tree
• Difficulty Level : Easy
• Last Updated : 02 Nov, 2020

We have given a binary search tree and we want to delete the leaf nodes from the binary search tree.

Examples:

```Input : 20 10 5 15 30 25 35
Output : Inorder before Deleting the leaf node
5 10 15 20 25 30 35
Inorder after Deleting the leaf node
10 20 30

This is the binary search tree where we
want to delete the leaf node.
20
/     \
10      30
/  \    /  \
5     15 25   35

After deleting the leaf node the binary
search tree looks like
20
/     \
10      30

```

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

We traverse given Binary Search Tree in inorder way. During traversal we check if current node is leaf, if yes, we delete it. Else we recur for left and right children. An important thing to remember is, we must assign new left and right children if there is any modification in roots of subtrees.

## C++

 `// C++ program to delete leaf Node from``// binary search tree.``#include ``using` `namespace` `std;`` ` `struct` `Node {``    ``int` `data;``    ``struct` `Node* left;``    ``struct` `Node* right;``};`` ` `// Create a newNode in binary search tree.``struct` `Node* newNode(``int` `data)``{``    ``struct` `Node* temp = ``new` `Node;``    ``temp->data = data;``    ``temp->left = temp->right = NULL;``    ``return` `temp;``}`` ` `// Insert a Node in binary search tree.``struct` `Node* insert(``struct` `Node* root, ``int` `data)``{``    ``if` `(root == NULL)``        ``return` `newNode(data);``    ``if` `(data < root->data)``        ``root->left = insert(root->left, data);``    ``else` `if` `(data > root->data)``        ``root->right = insert(root->right, data);``    ``return` `root;``}`` ` `// Function for inorder traversal in a BST.``void` `inorder(``struct` `Node* root)``{``    ``if` `(root != NULL) {``        ``inorder(root->left);``        ``cout << root->data << ``" "``;``        ``inorder(root->right);``    ``}``}`` ` `// Delete leaf nodes from binary search tree.``struct` `Node* leafDelete(``struct` `Node* root)``{``    ``if` `(root == NULL)``        ``return` `NULL;``    ``if` `(root->left == NULL && root->right == NULL) {``        ``free``(root);``        ``return` `NULL;``    ``}`` ` `    ``// Else recursively delete in left and right``    ``// subtrees.``    ``root->left = leafDelete(root->left);``    ``root->right = leafDelete(root->right);`` ` `    ``return` `root;``}`` ` `// Driver code``int` `main()``{``    ``struct` `Node* root = NULL;``    ``root = insert(root, 20);``    ``insert(root, 10);``    ``insert(root, 5);``    ``insert(root, 15);``    ``insert(root, 30);``    ``insert(root, 25);``    ``insert(root, 35);``    ``cout << ``"Inorder before Deleting the leaf Node."` `<< endl;``    ``inorder(root);``    ``cout << endl;``    ``leafDelete(root);``    ``cout << ``"INorder after Deleting the leaf Node."` `<< endl;``    ``inorder(root);``    ``return` `0;``}`

## Java

 `// Java program to delete leaf Node from``// binary search tree.``class` `GfG {`` ` `    ``static` `class` `Node {``        ``int` `data;``        ``Node left;``        ``Node right;``    ``}`` ` `    ``// Create a newNode in binary search tree.``    ``static` `Node newNode(``int` `data)``    ``{``        ``Node temp = ``new` `Node();``        ``temp.data = data;``        ``temp.left = ``null``;``        ``temp.right = ``null``;``        ``return` `temp;``    ``}`` ` `    ``// Insert a Node in binary search tree.``    ``static` `Node insert(Node root, ``int` `data)``    ``{``        ``if` `(root == ``null``)``            ``return` `newNode(data);``        ``if` `(data < root.data)``            ``root.left = insert(root.left, data);``        ``else` `if` `(data > root.data)``            ``root.right = insert(root.right, data);``        ``return` `root;``    ``}`` ` `    ``// Function for inorder traversal in a BST.``    ``static` `void` `inorder(Node root)``    ``{``        ``if` `(root != ``null``) {``            ``inorder(root.left);``            ``System.out.print(root.data + ``" "``);``            ``inorder(root.right);``        ``}``    ``}`` ` `    ``// Delete leaf nodes from binary search tree.``    ``static` `Node leafDelete(Node root)``    ``{``        ``if` `(root == ``null``) {``            ``return` `null``;``        ``}``        ``if` `(root.left == ``null` `&& root.right == ``null``) {``            ``return` `null``;``        ``}`` ` `        ``// Else recursively delete in left and right``        ``// subtrees.``        ``root.left = leafDelete(root.left);``        ``root.right = leafDelete(root.right);`` ` `        ``return` `root;``    ``}`` ` `    ``// Driver code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``Node root = ``null``;``        ``root = insert(root, ``20``);``        ``insert(root, ``10``);``        ``insert(root, ``5``);``        ``insert(root, ``15``);``        ``insert(root, ``30``);``        ``insert(root, ``25``);``        ``insert(root, ``35``);``        ``System.out.println(``"Inorder before Deleting the leaf Node. "``);``        ``inorder(root);``        ``System.out.println();``        ``leafDelete(root);``        ``System.out.println(``"INorder after Deleting the leaf Node. "``);``        ``inorder(root);``    ``}``}``// This code is contributed by Prerna saini`

## Python3

 `# Python 3 program to delete leaf``# Node from binary search tree. `` ` `# Create a newNode in binary search tree. ``class` `newNode: `` ` `    ``# Constructor to create a new node ``    ``def` `__init__(``self``, data): ``        ``self``.data ``=` `data ``        ``self``.left ``=` `None``        ``self``.right ``=` `None`` ` `# Insert a Node in binary search tree. ``def` `insert(root, data):``    ``if` `root ``=``=` `None``: ``        ``return` `newNode(data)``    ``if` `data < root.data:``        ``root.left ``=` `insert(root.left, data) ``    ``elif` `data > root.data: ``        ``root.right ``=` `insert(root.right, data) ``    ``return` `root`` ` `# Function for inorder traversal in a BST. ``def` `inorder(root):``    ``if` `root !``=` `None``: ``        ``inorder(root.left) ``        ``print``(root.data, end ``=` `" "``) ``        ``inorder(root.right)`` ` `# Delete leaf nodes from binary search tree. ``def` `leafDelete(root):``    ``if` `root ``=``=` `None``:``        ``return` `None``    ``if` `root.left ``=``=` `None` `and` `root.right ``=``=` `None``:``        ``return` `None`` ` `    ``# Else recursively delete in left ``    ``# and right subtrees. ``    ``root.left ``=` `leafDelete(root.left) ``    ``root.right ``=` `leafDelete(root.right)`` ` `    ``return` `root`` ` `# Driver code ``if` `__name__ ``=``=` `'__main__'``:``    ``root ``=` `None``    ``root ``=` `insert(root, ``20``) ``    ``insert(root, ``10``) ``    ``insert(root, ``5``)``    ``insert(root, ``15``) ``    ``insert(root, ``30``) ``    ``insert(root, ``25``) ``    ``insert(root, ``35``) ``    ``print``(``"Inorder before Deleting the leaf Node."``) ``    ``inorder(root)``    ``leafDelete(root)``    ``print``()``    ``print``(``"INorder after Deleting the leaf Node."``) ``    ``inorder(root)     `` ` `# This code is contributed by PranchalK`

## C#

 `// C# program to delete leaf Node from``// binary search tree.``using` `System;`` ` `class` `GfG {`` ` `    ``class` `Node {``        ``public` `int` `data;``        ``public` `Node left;``        ``public` `Node right;``    ``}`` ` `    ``// Create a newNode in binary search tree.``    ``static` `Node newNode(``int` `data)``    ``{``        ``Node temp = ``new` `Node();``        ``temp.data = data;``        ``temp.left = ``null``;``        ``temp.right = ``null``;``        ``return` `temp;``    ``}`` ` `    ``// Insert a Node in binary search tree.``    ``static` `Node insert(Node root, ``int` `data)``    ``{``        ``if` `(root == ``null``)``            ``return` `newNode(data);``        ``if` `(data < root.data)``            ``root.left = insert(root.left, data);``        ``else` `if` `(data > root.data)``            ``root.right = insert(root.right, data);``        ``return` `root;``    ``}`` ` `    ``// Function for inorder traversal in a BST.``    ``static` `void` `inorder(Node root)``    ``{``        ``if` `(root != ``null``) {``            ``inorder(root.left);``            ``Console.Write(root.data + ``" "``);``            ``inorder(root.right);``        ``}``    ``}`` ` `    ``// Delete leaf nodes from binary search tree.``    ``static` `Node leafDelete(Node root)``    ``{``        ``if` `(root == ``null``) {``            ``return` `null``;``        ``}``        ``if` `(root.left == ``null` `&& root.right == ``null``) {``            ``return` `null``;``        ``}`` ` `        ``// Else recursively delete in``        ``// left and right subtrees.``        ``root.left = leafDelete(root.left);``        ``root.right = leafDelete(root.right);`` ` `        ``return` `root;``    ``}`` ` `    ``// Driver code``    ``public` `static` `void` `Main(String[] args)``    ``{``        ``Node root = ``null``;``        ``root = insert(root, 20);``        ``insert(root, 10);``        ``insert(root, 5);``        ``insert(root, 15);``        ``insert(root, 30);``        ``insert(root, 25);``        ``insert(root, 35);``        ``Console.WriteLine(``"Inorder before Deleting"``                          ``+ ``"the leaf Node. "``);``        ``inorder(root);``        ``Console.WriteLine();``        ``leafDelete(root);``        ``Console.WriteLine(``"INorder after Deleting"``                          ``+ ``"the leaf Node. "``);``        ``inorder(root);``    ``}``}`` ` `// This code has been contributed``// by PrinciRaj1992`

Output:
```Inorder before Deleting the leaf node.
5 10 15 20 25 30 35
INorder after Deleting the leaf node.
10 20 30
```

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