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# Print the all leaf nodes in N ary tree

This article plunges into the intriguing realm of N-ary trees, unveiling the process of printing all the leaf nodes present within such trees. Through a detailed breakdown of the problem, the strategy to solve it, and the code implementation, readers will gain a comprehensive understanding of how to navigate and identify leaf nodes within N-ary trees.

## Problem Statement

Given an N-ary tree, the task is to print all the leaf nodes within the tree.

## Example

Consider the following N-ary tree:

``````
10
/  \
/    \
/      \
8        5
/|\     /|\
/ | \   / | \
-2 1  6 7 18 3 4
/ \         /| \
9  11       2 1 3
/  \
17   12``````

The output is:

``-2  9  17  12  6  7  18  3  2  1  3``

## Solution Strategy

1. Create a class `TreeNode` to represent nodes in the N-ary tree. This class should contain a value and a vector of children.
2. Implement the `NAryTree` class, responsible for building the N-ary tree and printing the leaf nodes.
3. Traverse the tree and print the value of nodes that have no children, i.e., leaf nodes.

## Code Solution

``````import java.util.Vector;
import java.util.ArrayList;
// Java program for
// Print the all leaf nodes in N-ary tree
class TreeNode
{
public int key;
public Vector < TreeNode > child;
public TreeNode(int key)
{
this.key = key;
this.child = new Vector < TreeNode > ();
}
{
TreeNode t = new TreeNode(key);
}
}
public class NAryTree
{
public TreeNode root;
public NAryTree()
{
// Set initial tree root to null
this.root = null;
}
// Print all leaf nodes
public void printLeafNode(TreeNode node)
{
if (node == null)
{
return;
}
int i = 0;
// iterating the child of given node
while (i < node.child.size())
{
// Recursively visit child node
printLeafNode(node.child.get(i));
i++;
}
if (node.child.size() == 0)
{
// When node is left node
System.out.print("  " + node.key);
}
}
public static void main(String[] args)
{
NAryTree tree = new NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree.root = new TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root);
}
}``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````// Include header file
#include <iostream>
#include <vector>
using namespace std;

// C++ program for
// Print the all leaf nodes in N-ary tree
class TreeNode
{
public: int key;
vector < TreeNode* > child;
TreeNode(int key)
{
this->key = key;
}
{
TreeNode *t = new TreeNode(key);
this->child.push_back(t);
}
};
class NAryTree
{
public: TreeNode *root;
NAryTree()
{
this->root = NULL;
}
// Print all leaf nodes
void printLeafNode(TreeNode *node)
{
if (node == NULL)
{
return;
}
int i = 0;
// iterating the child of given node
while (i < node->child.size())
{
// Recursively visit child node
this->printLeafNode(node->child.at(i));
i++;
}
if (node->child.size() == 0)
{
// When node is left node
cout << "  " << node->key;
}
}
};
int main()
{
NAryTree *tree = new NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree->root = new TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree->printLeafNode(tree->root);
return 0;
}``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````// Include namespace system
using System;
using System.Collections.Generic;

// Csharp program for
// Print the all leaf nodes in N-ary tree
public class TreeNode
{
public int key;
public List < TreeNode > child;
public TreeNode(int key)
{
this.key = key;
this.child = new List < TreeNode > ();
}
{
TreeNode t = new TreeNode(key);
}
}
public class NAryTree
{
public TreeNode root;
public NAryTree()
{
// Set initial tree root to null
this.root = null;
}
// Print all leaf nodes
public void printLeafNode(TreeNode node)
{
if (node == null)
{
return;
}
int i = 0;
// iterating the child of given node
while (i < node.child.Count)
{
// Recursively visit child node
this.printLeafNode(node.child[i]);
i++;
}
if (node.child.Count == 0)
{
// When node is left node
Console.Write("  " + node.key);
}
}
public static void Main(String[] args)
{
NAryTree tree = new NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree.root = new TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root);
}
}``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````<?php
// Php program for
// Print the all leaf nodes in N-ary tree
class TreeNode
{
public \$key;
public \$child;
public	function __construct(\$key)
{
\$this->key = \$key;
\$this->child = array();
}
{
\$t = new TreeNode(\$key);
\$this->child[] = \$t;
}
}
class NAryTree
{
public \$root;
public	function __construct()
{
\$this->root = NULL;
}
// Print all leaf nodes
public	function printLeafNode(\$node)
{
if (\$node == NULL)
{
return;
}
\$i = 0;
// iterating the child of given node
while (\$i < count(\$node->child))
{
// Recursively visit child node
\$this->printLeafNode(\$node->child[\$i]);
\$i++;
}
if (count(\$node->child) == 0)
{
// When node is left node
echo("  ".\$node->key);
}
}
}

function main()
{
\$tree = new NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
\$tree->root = new TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
\$tree->printLeafNode(\$tree->root);
}
main();``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````// Node JS program for
// Print the all leaf nodes in N-ary tree
class TreeNode
{
constructor(key)
{
this.key = key;
this.child = [];
}
{
var t = new TreeNode(key);
this.child.push(t);
}
}
class NAryTree
{
constructor()
{
this.root = null;
}
// Print all leaf nodes
printLeafNode(node)
{
if (node == null)
{
return;
}
var i = 0;
// iterating the child of given node
while (i < node.child.length)
{
// Recursively visit child node
this.printLeafNode(node.child[i]);
i++;
}
if (node.child.length == 0)
{
// When node is left node
process.stdout.write("  " + node.key);
}
}
}

function main()
{
var tree = new NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree.root = new TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root);
}
main();``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````#  Python 3 program for
#  Print the all leaf nodes in N-ary tree
class TreeNode :
def __init__(self, key) :
self.key = key
self.child = []

t = TreeNode(key)
self.child.append(t)

class NAryTree :
def __init__(self) :
self.root = None

#  Print all leaf nodes
def printLeafNode(self, node) :
if (node == None) :
return

i = 0
#  iterating the child of given node
while (i < len(node.child)) :
#  Recursively visit child node
self.printLeafNode(node.child[i])
i += 1

if (len(node.child) == 0) :
#  When node is left node
print("  ", node.key, end = "")

def main() :
tree = NAryTree()
#           10
#          /   \
#         /     \
#        /       \
#       8         5
#      /|\      /|\ \
#     / | \    / | \ \
#    -2 1  6  7 18 3  4
#      / \           /| \
#     9  11         2 1  3
#       /  \
#      17   12
#    -----------------------
#    Constructing N-Arr tree

#  First element of tree
tree.root = TreeNode(10)
#  Add child node [-2,1,5] in node (8)
#  Add child node [9,11] in node (1)
#  Add child node [17  12] in node (11)
#  Add child node [7 18 3  4] in node (5)
#  Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root)

if __name__ == "__main__": main()``````

#### input

``   -2   9   17   12   6   7   18   3   2   1   3``
``````#  Ruby program for
#  Print the all leaf nodes in N-ary tree
class TreeNode
# Define the accessor and reader of class TreeNode
attr_accessor :key, :child
def initialize(key)
self.key = key
self.child = []
end

t = TreeNode.new(key)
self.child.push(t)
end

end

class NAryTree
# Define the accessor and reader of class NAryTree
attr_accessor :root
def initialize()
self.root = nil
end

#  Print all leaf nodes
def printLeafNode(node)
if (node == nil)
return
end

i = 0
#  iterating the child of given node
while (i < node.child.length)
#  Recursively visit child node
self.printLeafNode(node.child[i])
i += 1
end

if (node.child.length == 0)
#  When node is left node
print("  ", node.key)
end

end

end

def main()
tree = NAryTree.new()
#           10
#          /   \
#         /     \
#        /       \
#       8         5
#      /|\      /|\ \
#     / | \    / | \ \
#    -2 1  6  7 18 3  4
#      / \           /| \
#     9  11         2 1  3
#       /  \
#      17   12
#    -----------------------
#    Constructing N-Arr tree
#  First element of tree
tree.root = TreeNode.new(10)
#  Add child node [-2,1,5] in node (8)
#  Add child node [9,11] in node (1)
#  Add child node [17  12] in node (11)
#  Add child node [7 18 3  4] in node (5)
#  Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root)
end

main()``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````import scala.collection.mutable._;
// Scala program for
// Print the all leaf nodes in N-ary tree
class TreeNode(var key: Int,
var child: ArrayBuffer[TreeNode])
{
def this(key: Int)
{
this(key, new ArrayBuffer[TreeNode]());
}
def addChild(key: Int): Unit = {
var t: TreeNode = new TreeNode(key);
this.child += t;
}
}
class NAryTree(var root: TreeNode)
{
def this()
{
this(null);
}
// Print all leaf nodes
def printLeafNode(node: TreeNode): Unit = {
if (node == null)
{
return;
}
var i: Int = 0;
// iterating the child of given node
while (i < node.child.size)
{
// Recursively visit child node
printLeafNode(node.child(i));
i += 1;
}
if (node.child.size == 0)
{
// When node is left node
print("  " + node.key);
}
}
}
object Main
{
def main(args: Array[String]): Unit = {
var tree: NAryTree = new NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree.root = new TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root);
}
}``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``
``````// Swift 4 program for
// Print the all leaf nodes in N-ary tree
class TreeNode
{
var key: Int;
var child: [TreeNode?] ;
init(_ key: Int)
{
self.key = key;
self.child = [TreeNode]();
}
{
let t: TreeNode = TreeNode(key);
self.child.append(t);
}
}
class NAryTree
{
var root: TreeNode? ;
init()
{
self.root = nil;
}
// Print all leaf nodes
func printLeafNode(_ node: TreeNode? )
{
if (node == nil)
{
return;
}
var i: Int = 0;
// iterating the child of given node
while (i < node!.child.count)
{
// Recursively visit child node
self.printLeafNode(node!.child[i]);
i += 1;
}
if (node!.child.count == 0)
{
// When node is left node
print("  ", node!.key, terminator: "");
}
}
}
func main()
{
let tree: NAryTree = NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree.root = TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root);
}
main();``````

#### input

``   -2   9   17   12   6   7   18   3   2   1   3``
``````// Kotlin program for
// Print the all leaf nodes in N-ary tree
class TreeNode
{
var key: Int;
var child: MutableList<TreeNode> ;
constructor(key: Int)
{
this.key = key;
this.child = mutableListOf<TreeNode>();
}
{
val t: TreeNode = TreeNode(key);
}
}
class NAryTree
{
var root: TreeNode ? ;
constructor()
{
this.root = null;
}
// Print all leaf nodes
fun printLeafNode(node: TreeNode ? ): Unit
{
if (node == null)
{
return;
}
var i: Int = 0;
// iterating the child of given node
while (i < node.child.size)
{
// Recursively visit child node
this.printLeafNode(node.child[i]);
i += 1;
}
if (node.child.size == 0)
{
// When node is left node
print("  " + node.key);
}
}
}
fun main(args: Array < String > ): Unit
{
val tree: NAryTree = NAryTree();
/*
10
/   \
/     \
/       \
8         5
/|\      /|\ \
/ | \    / | \ \
-2 1  6  7 18 3  4
/ \           /| \
9  11         2 1  3
/  \
17   12
-----------------------
Constructing N-Arr tree
*/
// First element of tree
tree.root = TreeNode(10);
// Add child node [-2,1,5] in node (8)
// Add child node [9,11] in node (1)
// Add child node [17  12] in node (11)
// Add child node [7 18 3  4] in node (5)
// Add child node [2,1,3] in node (7)
tree.printLeafNode(tree.root);
}``````

#### input

``  -2  9  17  12  6  7  18  3  2  1  3``

## Time Complexity Analysis

In the worst case, the traversal of the N-ary tree requires visiting each node once. Since the tree's depth is limited, the time complexity is O(n), where n is the number of nodes in the tree.

## Comment

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