Replace every node with depth in N-ary Generic Tree

Last Updated : 06 Dec, 2023

Given an array arr[] representing a Generic(N-ary) tree. The task is to replace the node data with the depth(level) of the node. Assume level of root to be 0.

Array Representation: The N-ary tree is serialized in the array arr[] using level order traversal as described below:

The input is given as a level order traversal of N-ary Tree.

The first element of the array arr[] is the root node.

Then, followed by a number N, which denotes the number of children of the previous node. Value zero denotes Null Node.

Examples:

Input: arr[] = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 }
Below is the N-ary Tree of the above array level order traversal:

Output:
Below is the representation of the above output:

Input: arr[] = {1, 3, 2, 3, 4, 2, 5, 6, 0, 0, 2, 8, 9, 0}
Below is the N-ary Tree of the above array level order traversal:

Output:
Below is the representation of the above output:

Approach:

Traverse the tree starting from root.
While traversing pass depth of node as a parameter.
Track depth by passing it as 0 for root and (1 + current level) for children.

Below is the implementation of the above approach:

CPP

// C++ program to implement node with
// it's depth value
#include <bits/stdc++.h>
using namespace std;
 
// Treenode class using template
template <typename T>
class TreeNode {
public:
    // To store node value
    T data;
 
    // Pointer to TreeNode to store
    // the child node
    vector<TreeNode<T>*> children;
 
    // Constructor to assign data
    // to node
    TreeNode(T data)
    {
        this->data = data;
    }
 
    // Destructors to delete a node
    ~TreeNode()
    {
        for (int i = 0;
             i < children.size(); i++) {
            delete children[i];
        }
    }
};
 
// Function to take input level wise
// i.e., in level order traversal
TreeNode<int>* takeInputLevelWise(int arr[])
{
    int idx = 1;
 
    // Input root
    int rootData = arr[0];
 
    // Initialize tree with a root node
    TreeNode<int>* root
        = new TreeNode<int>(rootData);
 
    // Initialise queue for appending
    // node as a child of parent in
    // N-ary tree
    queue<TreeNode<int>*> pendingNodes;
 
    // Push the root node in queue
    pendingNodes.push(root);
 
    // While queue is not empty append
    // child to the root
    while (pendingNodes.size() != 0) {
 
        // Take the first node
        TreeNode<int>* front
            = pendingNodes.front();
        pendingNodes.pop();
 
        // Input number of child
        int numChild = arr[idx];
        idx++;
 
        for (int i = 0; i < numChild; i++) {
 
            int childData = arr[idx];
            idx++;
 
            // Make child Node
            TreeNode<int>* child
                = new TreeNode<int>(childData);
 
            // Append child node to
            // it's parent
            front->children.push_back(child);
            pendingNodes.push(child);
        }
    }
    return root;
}
 
// Function to print each node data
// in level order
void printLevelATNewLine(TreeNode<int>* root)
{
    queue<TreeNode<int>*> q;
    q.push(root);
    q.push(NULL);
    while (!q.empty()) {
 
        TreeNode<int>* first = q.front();
        q.pop();
 
        if (first == NULL) {
            if (q.empty()) {
                break;
            }
            cout << endl;
            q.push(NULL);
            continue;
        }
 
        cout << first->data << " ";
 
        for (int i = 0;
             i < first->children.size(); i++) {
            q.push(first->children[i]);
        }
    }
}
 
// Helper function to replace the
// node data with their level value
void helper(TreeNode<int>* root,
            int depth)
{
 
    // Replace the node data with
    // it's depth
    root->data = depth;
    for (int i = 0;
         i < root->children.size(); i++) {
 
        helper(root->children[i], depth + 1);
    }
}
 
// Function to replace with depth
void replaceWithDepthValue(TreeNode<int>* root)
{
    helper(root, 0);
}
 
// Driver Code
int main()
{
 
    // Given level order traversal in
    // the array arr[]
    int arr[] = { 1, 3, 2, 3, 4, 2, 5, 6, 0, 0, 2, 8, 9, 0};
 
    // Initialise Tree
    TreeNode<int>* root;
    root = takeInputLevelWise(arr);
 
    // Function call to replace with
    // depth value
    replaceWithDepthValue(root);
 
    // Function call to print
    // in level order
    printLevelATNewLine(root);
    return 0;
}

Java

// Java program to replace node with
// it's depth value
 
// Importing classes and interface
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
 
class GFG {
    // TreeNode class
    static class TreeNode<T> {
        // To store node value
        T data;
 
        // List of TreeNode to store
        // the child nodes
        ArrayList<TreeNode<T> > children;
 
        // Constructor to assign data to node
        TreeNode(T data)
        {
            this.data = data;
            children = new ArrayList<TreeNode<T> >();
        }
    }
 
    // Function to take input level wise
    // i.e., in level order traversal
    static TreeNode<Integer> takeInputLevelWise(int arr[])
    {
        int idx = 1;
 
        // Input root
        int rootData = arr[0];
 
        // Initialize tree with a root node
        TreeNode<Integer> root
            = new TreeNode<Integer>(rootData);
 
        // Initialize queue for appending
        // node as a child of parent in
        // N-ary tree
        Queue<TreeNode<Integer> > pendingNodes
            = new LinkedList<TreeNode<Integer> >();
 
        // Push the root node in queue
        pendingNodes.add(root);
 
        // While queue is not empty append
        // child to the node
        while (pendingNodes.size() != 0) {
 
            // Take the first node
            TreeNode<Integer> front = pendingNodes.peek();
            pendingNodes.poll();
 
            // Input number of its child
            int numChild = arr[idx];
            idx++;
 
            for (int i = 0; i < numChild; i++) {
                int childData = arr[idx];
                idx++;
 
                // Make child Node
                TreeNode<Integer> child
                    = new TreeNode<Integer>(childData);
 
                // Append child node to
                // it's parent
                front.children.add(child);
                pendingNodes.add(child);
            }
        }
        return root;
    }
 
    // Function to print each node data
    // in level order
    static void printLevelATNewLine(TreeNode<Integer> root)
    {
        Queue<TreeNode<Integer> > q
            = new LinkedList<TreeNode<Integer> >();
        q.add(root);
        q.add(null);
        while (!q.isEmpty()) {
            TreeNode<Integer> first = q.peek();
            q.poll();
 
            if (first == null) {
                // If there is no more nodes
                if (q.isEmpty()) {
                    break;
                }
                // All the nodes of current level are
                // visited
                System.out.println();
                q.add(null);
                continue;
            }
 
            System.out.print(first.data + " ");
 
            // Append current node's child to queue
            for (int i = 0; i < first.children.size();
                 i++) {
                q.add(first.children.get(i));
            }
        }
    }
 
    // Helper function to replace the
    // node data with their level value
    static void helper(TreeNode<Integer> root, int depth)
    {
        // Replace the node data with
        // it's depth
        root.data = depth;
        for (int i = 0; i < root.children.size(); i++) {
            helper(root.children.get(i), depth + 1);
        }
    }
 
    // Function to replace with depth
    static void
    replaceWithDepthValue(TreeNode<Integer> root)
    {
        helper(root, 0);
    }
 
    // Driver Code
    public static void main(String[] args)
    {
        // Given level order traversal in
        // the array arr[]
        int arr[]
            = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 };
 
        // Initialise Tree
        TreeNode<Integer> root;
        root = takeInputLevelWise(arr);
 
        // Function call to replace with
        // depth value
        replaceWithDepthValue(root);
 
        // Function call to print
        // in level order
        printLevelATNewLine(root);
    }
}
 
// This code is contributed by jainlovely450

Python3

# Python code for the above approach
from typing import List, Tuple
 
# TreeNode class
class TreeNode:
   
    # To store node value
    data: int
     
    # List of TreeNode to store
    # the child nodes
    children: List['TreeNode']
 
    # Constructor to assign data to node
    def __init__(self, data: int):
        self.data = data
        self.children = []
 
# Function to take input level wise
# i.e., in level order traversal
def take_input_level_wise(arr: List[int]) -> TreeNode:
    idx = 1
     
    # Input root
    root_data = arr[0]
     
    # Initialize tree with a root node
    root = TreeNode(root_data)
     
    # Initialize queue for appending
    # node as a child of parent in
    # N-ary tree
    pending_nodes = [root]
     
    # While queue is not empty append
    # child to the node
    while pending_nodes:
       
        # Take the first node
        front = pending_nodes[0]
        pending_nodes = pending_nodes[1:]
         
        # Input number of its child
        num_child = arr[idx]
        idx += 1
        for i in range(num_child):
            child_data = arr[idx]
            idx += 1
             
            # Make child Node
            child = TreeNode(child_data)
             
            # Append child node to
            # it's parent
            front.children.append(child)
            pending_nodes.append(child)
    return root
 
# Function to print each node data
# in level order
def print_level_at_new_line(root: TreeNode):
    q = [root]
    q.append(None)
    while q:
        first = q[0]
        q = q[1:]
        if first is None:
           
            # If there is no more nodes
            if not q:
                break
                 
            # All the nodes of current level are
            # visited
            print()
            q.append(None)
            continue
        print(first.data, end=' ')
         
        # Append current node's child to queue
        for i in range(len(first.children)):
            q.append(first.children[i])
 
# Helper function to replace the
# node data with their level value
def helper(root: TreeNode, depth: int):
   
    # Replace the node data with
    # it's depth
    root.data = depth
    for i in range(len(root.children)):
        helper(root.children[i], depth + 1)
 
# Function to replace with depth
def replace_with_depth_value(root: TreeNode):
    helper(root, 0)
 
 
# Driver Code
if __name__ == '__main__':
   
    # Given level order traversal in
    # the array arr[]
    arr = [10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0]
 
    # Initialise Tree
    root = take_input_level_wise(arr)
 
    # Function call to replace with
    # depth value
    replace_with_depth_value(root)
 
    # Print the tree in level order
    print_level_at_new_line(root)
     
# This code is contributed by Potta Lokesh

C#

using System;
using System.Collections.Generic;
 
// Class to represent a node with data and its children in
// N-ary tree
class TreeNode<T> {
    public T Data
    {
        get;
        set;
    }
    public List<TreeNode<T> > Children
    {
        get;
        set;
    }
 
    public TreeNode(T data)
    {
        this.Data = data;
        this.Children = new List<TreeNode<T> >();
    }
}
 
class GFG {
    static void Main(string[] args)
    {
        // Input level order data
        int[] arr
            = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 };
 
        // Initialize Tree with root node
        var root = TakeInputLevelWise(arr);
 
        // Replace the node data with their depth value
        ReplaceWithDepthValue(root, 0);
 
        // Print level order
        PrintLevelAtNewLine(root);
    }
 
    // Function to take input level wise
    static TreeNode<int> TakeInputLevelWise(int[] arr)
    {
        int idx = 1;
 
        // Input root data
        int rootData = arr[0];
        var root = new TreeNode<int>(rootData);
 
        // Initialise queue for appending node as a child of
        // parent
        var pendingNodes = new Queue<TreeNode<int> >();
 
        // Push the root node in queue
        pendingNodes.Enqueue(root);
 
        // While queue is not empty append child to the root
        while (pendingNodes.Count != 0) {
            // Take the first node
            var front = pendingNodes.Dequeue();
 
            // Input number of children
            int numChild = arr[idx];
            idx++;
 
            for (int i = 0; i < numChild; i++) {
                int childData = arr[idx];
                idx++;
 
                // Make child node
                var child = new TreeNode<int>(childData);
 
                // Append child node to its parent
                front.Children.Add(child);
                pendingNodes.Enqueue(child);
            }
        }
 
        return root;
    }
 
    // Function to print level order
    static void PrintLevelAtNewLine(TreeNode<int> root)
    {
        var q = new Queue<TreeNode<int> >();
        q.Enqueue(root);
        q.Enqueue(null);
 
        while (q.Count != 0) {
            var first = q.Dequeue();
 
            if (first == null) {
                if (q.Count == 0) {
                    break;
                }
 
                Console.WriteLine();
                q.Enqueue(null);
                continue;
            }
 
            Console.Write(first.Data + " ");
 
            foreach(var child in first.Children)
            {
                q.Enqueue(child);
            }
        }
    }
 
    // Function to replace node data with their depth value
    static void ReplaceWithDepthValue(TreeNode<int> root,
                                      int depth)
    {
        root.Data = depth;
 
        foreach(var child in root.Children)
        {
            ReplaceWithDepthValue(child, depth + 1);
        }
    }
}
//This Code is Contributed by chinmaya121221

Javascript

// JavaScript program to replace node with it's depth value
 
// TreeNode class
class TreeNode {
  constructor(data) {
   
    // To store node value
    this.data = data;
     
    // List of TreeNode to store the child nodes
    this.children = [];
  }
}
 
// Function to take input level wise i.e., in level order traversal
function takeInputLevelWise(arr) {
  let idx = 1;
 
  // Input root
  let rootData = arr[0];
 
  // Initialize tree with a root node
  const root = new TreeNode(rootData);
 
  // Initialize queue for appending node as a child of parent in N-ary tree
  const pendingNodes = [];
 
  // Push the root node in queue
  pendingNodes.push(root);
 
  // While queue is not empty append child to the node
  while (pendingNodes.length !== 0) {
    // Take the first node
    const front = pendingNodes.shift();
 
    // Input number of its child
    const numChild = arr[idx];
    idx++;
 
    for (let i = 0; i < numChild; i++) {
      const childData = arr[idx];
      idx++;
 
      // Make child Node
      const child = new TreeNode(childData);
 
      // Append child node to it's parent
      front.children.push(child);
      pendingNodes.push(child);
    }
  }
  return root;
}
 
// Function to print each node data in level order
function printLevelATNewLine(root) {
  const q = [];
  q.push(root);
  q.push(null);
  while (q.length !== 0) {
    const first = q.shift();
 
    if (first === null) {
      // If there is no more nodes
      if (q.length === 0) {
        break;
      }
       
      // All the nodes of current level are visited
      console.log("<br>");
      q.push(null);
      continue;
    }
 
    console.log(first.data + " ");
 
    // Append current node's child to queue
    for (let i = 0; i < first.children.length; i++) {
      q.push(first.children[i]);
    }
  }
}
 
// Helper function to replace the node data with their level value
function helper(root, depth) {
 
  // Replace the node data with it's depth
  root.data = depth;
  for (let i = 0; i < root.children.length; i++) {
    helper(root.children[i], depth + 1);
  }
}
 
// Function to replace with depth
function replaceWithDepthValue(root) {
  helper(root, 0);
}
 
// Given level order traversal in the array arr[]
const arr = [10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0];
 
// Initialise Tree
let root = takeInputLevelWise(arr);
 
// Function call to replace with depth value
replaceWithDepthValue(root);
 
// Function call to print in level order
printLevelATNewLine(root);
 
// This code is contributed by sankar.

Output

0 
1 1 1 
2 2

Time Complexity: O(N), where N is the number of nodes in Tree.
Auxiliary Space: O(N), where N is the number of nodes in Tree.

Another Approach: We can also replace the node’s value with its depth while creating the tree. We are traversing the array level wise which means that nodes currently present in the queue are of the same depth. As we append its child nodes to the queue, they will be present in the next level. We can initialize a variable as current depth equal to 1 and when we create child node we can assign its value to current depth level. After traversing all the nodes present in the current level we will increment current depth level by 1.

C++

// C++ program to implement node with
// it's depth value
#include <bits/stdc++.h>
using namespace std;
 
// Treenode class using template
template <typename T> class TreeNode {
public:
    // To store node value
    T data;
 
    // Pointer to TreeNode to store
    // the child node
    vector<TreeNode<T>*> children;
 
    // Constructor to assign data
    // to node
    TreeNode(T data) { this->data = data; }
 
    // Destructors to delete a node
    ~TreeNode()
    {
        for (int i = 0; i < children.size(); i++) {
            delete children[i];
        }
    }
};
 
// Function to take input level wise
// i.e., in level order traversal
TreeNode<int>* takeInputLevelWise(int arr[])
{
    int idx = 1;
    int depthLevel = 1;
 
    // Initialize tree with a root node
    // with depth 0
    TreeNode<int>* root = new TreeNode<int>(0);
 
    // Initialise queue for appending
    // node as a child of parent in
    // N-ary tree
    queue<TreeNode<int>*> pendingNodes;
 
    // Push the root node in queue
    pendingNodes.push(root);
 
    // While queue is not empty append
    // child to the node
    while (pendingNodes.size() != 0) {
        // Number of nodes present in the current level
        int size = pendingNodes.size();
 
        while (size > 0) {
            // Take the first node
            TreeNode<int>* front = pendingNodes.front();
            pendingNodes.pop();
 
            // Input number of its child
            int numChild = arr[idx];
            idx++;
 
            for (int i = 0; i < numChild; i++) {
                idx++;
                // Make child Node and assign its data
                // value equal to depthLevel
                TreeNode<int>* child
                    = new TreeNode<int>(depthLevel);
 
                // Append child node to
                // it's parent
                front->children.push_back(child);
                pendingNodes.push(child);
            }
            size--;
        }
        // Increment depth level
        depthLevel++;
    }
    return root;
}
 
// Function to print each node data
// in level order
void printLevelATNewLine(TreeNode<int>* root)
{
    queue<TreeNode<int>*> q;
    q.push(root);
    q.push(NULL);
    while (!q.empty()) {
        TreeNode<int>* first = q.front();
        q.pop();
 
        if (first == NULL) {
            // If there is no more nodes to visit
            if (q.empty()) {
                break;
            }
            // All the nodes of current level are visited
            cout << endl;
            q.push(NULL);
            continue;
        }
 
        cout << first->data << " ";
        // Append current node's child to queue
        for (int i = 0; i < first->children.size(); i++) {
            q.push(first->children[i]);
        }
    }
}
 
// Driver Code
int main()
{
    // Given level order traversal in
    // the array arr[]
    int arr[]
        = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 };
 
    // Initialise Tree
    TreeNode<int>* root;
    root = takeInputLevelWise(arr);
 
    // Function call to print
    // in level order
    printLevelATNewLine(root);
    return 0;
}
 
// This code is contributed by jainlovely450

Java

// Java program to implement node with
// it's depth value
 
// Importing classes and interface
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
 
public class GFG {
 
    // TreeNode class
    static class TreeNode<T> {
        // To store node value
        T data;
 
        // List of TreeNode to store
        // the child nodes
        ArrayList<TreeNode<T> > children;
 
        // Constructor to assign data to node
        TreeNode(T data)
        {
            this.data = data;
            children = new ArrayList<TreeNode<T> >();
        }
    }
 
    // Function to take input level wise
    // i.e., in level order traversal and
    // assign value of node equal to its depth
    static TreeNode<Integer> takeInputLevelWise(int arr[])
    {
        int idx = 1;
        int depthLevel = 1;
         
      // Initialize tree with a root node
        // with depth 0
        TreeNode<Integer> root = new TreeNode<Integer>(0);
        
        // Initialize queue for appending
        // node as a child of parent in
        // N-ary tree
        Queue<TreeNode<Integer> > pendingNodes
            = new LinkedList<TreeNode<Integer> >();
 
        // Push the root node in queue
        pendingNodes.add(root);
 
        // While queue is not empty append
        // child to the node
        while (!pendingNodes.isEmpty()) {
            // Number of nodes present in the current level
            int size = pendingNodes.size();
 
            while (size > 0) {
                TreeNode<Integer> front
                    = pendingNodes.peek();
                pendingNodes.poll();
 
                // Input number of child
                int numChild = arr[idx];
                idx++;
                for (int i = 0; i < numChild; i++) {
                    idx++;
 
                    // Make child Node and assign its data
                    // value equal to depthLevel
                    TreeNode<Integer> child
                        = new TreeNode<Integer>(depthLevel);
 
                    // Append child node to
                    // it's parent
                    front.children.add(child);
                    pendingNodes.add(child);
                }
                size--;
            }
            // Increment depth level
            depthLevel++;
        }
        return root;
    }
 
    // Function to print each node data
    // in level order
    static void printLevelATNewLine(TreeNode<Integer> root)
    {
        Queue<TreeNode<Integer> > q
            = new LinkedList<TreeNode<Integer> >();
        q.add(root);
        q.add(null);
        while (!q.isEmpty()) {
            TreeNode<Integer> first = q.peek();
            q.poll();
            if (first == null) {
                // If there is no more nodes to visit
                if (q.isEmpty()) {
                    break;
                }
                // All the nodes of current level are
                // visited
                System.out.println();
                q.add(null);
                continue;
            }
 
            System.out.print(first.data + " ");
 
            // Append current node's child to queue
            for (int i = 0; i < first.children.size();
                 i++) {
                q.add(first.children.get(i));
            }
        }
    }
 
    // Driver Code
    public static void main(String[] args)
    {
 
        // Given level order traversal in
        // the array arr[]
        int arr[]
            = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 };
 
        // Initialize Tree
        TreeNode<Integer> root;
        root = takeInputLevelWise(arr);
 
        // Function call to print
        // in level order
        printLevelATNewLine(root);
    }
}
 
// This code is contributed by jainlovely450

Python3

# Python code
 
# TreeNode class
class TreeNode:
  # To store node value
  def __init__(self, data):
    self.data = data
    # List of TreeNode to store
    # the child nodes
    self.children = []
 
# Function to take input level wise
# i.e., in level order traversal and
# assign value of node equal to its depth
def takeInputLevelWise(arr):
  idx = 1
  depthLevel = 1
   
  # Initialize tree with a root node
  # with depth 0
  root = TreeNode(0)
  
  # Initialize queue for appending
  # node as a child of parent in
  # N-ary tree
  pendingNodes = []
  pendingNodes.append(root)
 
  # While queue is not empty append
  # child to the node
  while pendingNodes:
    # Number of nodes present in the current level
    size = len(pendingNodes)
 
    while size > 0:
      front = pendingNodes[0]
      pendingNodes.pop(0)
 
      # Input number of child
      numChild = arr[idx]
      idx += 1
      for i in range(numChild):
        idx += 1
 
        # Make child Node and assign its data
        # value equal to depthLevel
        child = TreeNode(depthLevel)
 
        # Append child node to
        # it's parent
        front.children.append(child)
        pendingNodes.append(child)
      size -= 1
    # Increment depth level
    depthLevel += 1
  return root
 
# Function to print each node data
# in level order
def printLevelATNewLine(root):
  q = []
  q.append(root)
  q.append(None)
  while q:
    first = q[0]
    q.pop(0)
    if first is None:
      # If there is no more nodes to visit
      if not q:
        break
      # All the nodes of current level are
      # visited
      print()
      q.append(None)
      continue
    print(first.data, end=" ")
 
    # Append current node's child to queue
    for i in range(len(first.children)):
      q.append(first.children[i])
 
# Driver Code
if __name__ == '__main__':
  # Given level order traversal in
  # the array arr[]
  arr = [10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0]
 
  # Initialize Tree
  root = takeInputLevelWise(arr)
 
  # Function call to print
  # in level order
  printLevelATNewLine(root)

C#

// C# program to implement node with it's depth value
 
using System;
using System.Collections.Generic;
 
public class GFG {
 
    // TreeNode class
    class TreeNode<T> {
        // To store node value
        public T data;
 
        // List of TreeNode to store
        // the child nodes
        public List<TreeNode<T> > children;
 
        // Constructor to assign data to node
        public TreeNode(T data)
        {
            this.data = data;
            children = new List<TreeNode<T> >();
        }
    }
 
    // Function to take input level wise i.e., in level
    // order traversal and assign value of node equal to its
    // depth
    static TreeNode<int> takeInputLevelWise(int[] arr)
    {
        int idx = 1;
        int depthLevel = 1;
 
        // Initialize tree with a root node with depth 0
        TreeNode<int> root = new TreeNode<int>(0);
 
        // Initialize queue for appending node as a child of
        // parent in N-ary tree
        Queue<TreeNode<int> > pendingNodes
            = new Queue<TreeNode<int> >();
 
        // Push the root node in queue
        pendingNodes.Enqueue(root);
 
        // While queue is not empty append child to the node
        while (pendingNodes.Count != 0) {
            // Number of nodes present in the current level
            int size = pendingNodes.Count;
 
            while (size > 0) {
                TreeNode<int> front = pendingNodes.Peek();
                pendingNodes.Dequeue();
 
                // Input number of child
                int numChild = arr[idx];
                idx++;
                for (int i = 0; i < numChild; i++) {
                    idx++;
 
                    // Make child Node and assign its data
                    // value equal to depthLevel
                    TreeNode<int> child
                        = new TreeNode<int>(depthLevel);
 
                    // Append child node to it's parent
                    front.children.Add(child);
                    pendingNodes.Enqueue(child);
                }
                size--;
            }
            // Increment depth level
            depthLevel++;
        }
        return root;
    }
 
    // Function to print each node data in level order
    static void printLevelATNewLine(TreeNode<int> root)
    {
        Queue<TreeNode<int> > q
            = new Queue<TreeNode<int> >();
        q.Enqueue(root);
        q.Enqueue(null);
        while (q.Count != 0) {
            TreeNode<int> first = q.Peek();
            q.Dequeue();
            if (first == null) {
                // If there is no more nodes to visit
                if (q.Count == 0) {
                    break;
                }
                // All the nodes of current level are
                // visited
                Console.WriteLine();
                q.Enqueue(null);
                continue;
            }
 
            Console.Write(first.data + " ");
 
            // Append current node's child to queue
            for (int i = 0; i < first.children.Count; i++) {
                q.Enqueue(first.children[i]);
            }
        }
    }
 
    static public void Main()
    {
 
        // Code
        // Given level order traversal in the array arr[]
        int[] arr
            = { 10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0 };
 
        // Initialize Tree
        TreeNode<int> root;
        root = takeInputLevelWise(arr);
 
        // Function call to print in level order
        printLevelATNewLine(root);
    }
}
 
// This code is contributed by karthik.

Javascript

<script>
 
// JavaScript program to implement node with
// it's depth value
 
// TreeNode class
class TreeNode {
  // To store node value
  constructor(data) {
    this.data = data;
    // List of TreeNode to store
    // the child nodes
    this.children = [];
  }
}
 
// Function to take input level wise
// i.e., in level order traversal and
// assign value of node equal to its depth
function takeInputLevelWise(arr) {
  let idx = 1;
  let depthLevel = 1;
 
  // Initialize tree with a root node
  // with depth 0
  const root = new TreeNode(0);
 
  // Initialize queue for appending
  // node as a child of parent in
  // N-ary tree
  const pendingNodes = [];
 
  // Push the root node in queue
  pendingNodes.push(root);
 
  // While queue is not empty append
  // child to the node
  while (pendingNodes.length !== 0) {
    // Number of nodes present in the current level
    let size = pendingNodes.length;
 
    while (size > 0) {
      const front = pendingNodes.shift();
 
      // Input number of child
      const numChild = arr[idx];
      idx++;
      for (let i = 0; i < numChild; i++) {
        idx++;
 
        // Make child Node and assign its data
        // value equal to depthLevel
        const child = new TreeNode(depthLevel);
 
        // Append child node to
        // it's parent
        front.children.push(child);
        pendingNodes.push(child);
      }
      size--;
    }
    // Increment depth level
    depthLevel++;
  }
  return root;
}
 
// Function to print each node data
// in level order
function printLevelATNewLine(root) {
  const q = [];
  q.push(root);
  q.push(null);
  while (q.length !== 0) {
    const first = q.shift();
    if (first === null) {
      // If there is no more nodes to visit
      if (q.length === 0) {
        break;
      }
      // All the nodes of current level are
      // visited
      document.write("<br>");
      q.push(null);
      continue;
    }
 
    document.write(first.data + " ");
 
    // Append current node's child to queue
    for (let i = 0; i < first.children.length; i++) {
      q.push(first.children[i]);
    }
  }
  document.write("<br>")
}
 
// Given level order traversal in
// the array arr[]
const arr = [10, 3, 20, 30, 40, 2, 40, 50, 0, 0, 0, 0];
 
// Initialize Tree
const root = takeInputLevelWise(arr);
 
// Function call to print
// in level order
printLevelATNewLine(root);
 
// This code is contributed by karthik.
 
</script>

Output

0 
1 1 1 
2 2

Time Complexity: O(N), where N is the number of nodes in Tree.
Auxiliary Space: O(N), where N is the number of nodes in Tree.

Suggest improvement

Check mirror in n-ary tree

Preorder Traversal of N-ary Tree Without Recursion

Share your thoughts in the comments

N-ary Tree Traversals

Easy problems on n-ary Tree

Intermediate problems on n-ary Tree

Hard problems on n-ary Tree

N-ary Tree Traversals

Easy problems on n-ary Tree

Intermediate problems on n-ary Tree

Hard problems on n-ary Tree

Replace every node with depth in N-ary Generic Tree

CPP

Java

Python3

C#

Javascript

C++

Java

Python3

C#

Javascript

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