Check if a node is an Internal Node or not

Given a binary tree, for each node check whether it is an internal node or not.

Examples:

Input:

Example-1

Output: Node A: True
Node B: True
Node C: False
Node D: False
Explanation: In this illustration, Node A possesses two child nodes (B and C) which categorizes it as a node. On the other hand, both Nodes B possess one child node D, and C is a leaf node since they lack any child nodes.

Input:

Example-2

Output: Node X: True
Node Y: False
Node Z: False
Explanation: In this illustration, Node X possesses two child nodes (Y and Z) which categorizes it as a node. On the other hand, both Nodes Y and Z are leaf nodes since they lack any child nodes.

Approach: To solve the problem follow the below steps:

• Traverse the tree starting from the root node.
• For every encountered node, during traversal check if it has any child nodes or not.
• If the node has at least one child classify it as an internal node; otherwise consider it a leaf node.
• Check for at least one child if either left or right or both exist then the node is an internal node.

Below is the implementation of the above approach:

C++

// C++ implementation
#include <iostream>
#include <vector>

class TreeNode {
public:
    std::string value;
    std::vector<TreeNode*> childNodes;

    TreeNode(std::string val) {
        value = val;
    }
};

bool checkNode(TreeNode* currNode) {
    return currNode->childNodes.size() > 0;
}

int main() {
    // Defining the tree node class
    TreeNode* root = new TreeNode("A");
    root->childNodes.push_back(new TreeNode("B"));
    root->childNodes.push_back(new TreeNode("C"));
    root->childNodes[0]->childNodes.push_back(new TreeNode("D"));

    // Checking internal nodes
    std::cout << checkNode(root) << std::endl;
    std::cout << checkNode(root->childNodes[0]) << std::endl;
    std::cout << checkNode(root->childNodes[1]) << std::endl;
    std::cout << checkNode(root->childNodes[0]->childNodes[0]) << std::endl;

    return 0;
}

// This code is contributed by Tapesh(tapeshdua420)

Java

import java.util.ArrayList;
import java.util.List;

class TreeNode {
    String value;
    List<TreeNode> childNodes;

    // TreeNode class constructor
    public TreeNode(String val) {
        value = val;
        childNodes = new ArrayList<>();
    }
}

public class Main {
    // Function to check if the TreeNode has child nodes
    public static boolean checkNode(TreeNode currNode) {
        return currNode.childNodes.size() > 0;
    }

    public static void main(String[] args) {
        // Defining the tree node class

        // Creating the root node 'A'
        TreeNode root = new TreeNode("A");

        // Adding child nodes 'B' and 'C' to the root
        root.childNodes.add(new TreeNode("B"));
        root.childNodes.add(new TreeNode("C"));

        // Adding a child node 'D' to node 'B'
        root.childNodes.get(0).childNodes.add(new TreeNode("D"));

        // Checking internal nodes

        // Checking if the root node has child nodes
        System.out.println(checkNode(root));

        // Checking if node 'B' has child nodes
        System.out.println(checkNode(root.childNodes.get(0)));

        // Checking if node 'C' has child nodes
        System.out.println(checkNode(root.childNodes.get(1)));

        // Checking if node 'D' has child nodes
        System.out.println(checkNode(root.childNodes.get(0).childNodes.get(0)));
    }
}

Python

# Defining the tree node class
class tree:
    def __init__(self, val):
        self.value = val
        self.childnode = []

# Here we will check if the node is
# internal or not


def checkNode(currNode):
    return len(currNode.childnode) > 0


# Now we are adding nodes in the tree
root = tree("A")
root.childnode.append(tree("B"))
root.childnode.append(tree("C"))
root.childnode[0].childnode.append(tree("D"))

# Checking internal nodes
print(checkNode(root))
print(checkNode(root.childnode[0]))
print(checkNode(root.childnode[1]))
print(checkNode(root.childnode[0].childnode[0]))

C#

using System;
using System.Collections.Generic;

// Defining the tree node class
class TreeNode
{
    public string Value { get; set; }
    public List<TreeNode> ChildNodes { get; }

    public TreeNode(string val)
    {
        Value = val;
        ChildNodes = new List<TreeNode>();
    }
}

class MainClass
{
    // Here we will check if the node is internal or not
    static bool CheckNode(TreeNode currNode)
    {
        return currNode.ChildNodes.Count > 0;
    }

    public static void Main(string[] args)
    {
        // Now we are adding nodes in the tree
        TreeNode root = new TreeNode("A");
        root.ChildNodes.Add(new TreeNode("B"));
        root.ChildNodes.Add(new TreeNode("C"));
        root.ChildNodes[0].ChildNodes.Add(new TreeNode("D"));

        // Checking internal nodes
        Console.WriteLine(CheckNode(root)); // Output: True
        Console.WriteLine(CheckNode(root.ChildNodes[0])); // Output: True
        Console.WriteLine(CheckNode(root.ChildNodes[1])); // Output: False
        Console.WriteLine(CheckNode(root.ChildNodes[0].ChildNodes[0])); // Output: False
    }
}

Javascript

// Define the tree node class
class TreeNode {
    constructor(val) {
        this.value = val;
        this.childNodes = [];
    }
}

// Function to check if a node is internal or not
function checkNode(currNode) {
    return currNode.childNodes.length > 0;
}

// Create the root node and build the tree structure
const root = new TreeNode("A");
root.childNodes.push(new TreeNode("B"));
root.childNodes.push(new TreeNode("C"));
root.childNodes[0].childNodes.push(new TreeNode("D"));

// Checking if the nodes are internal
console.log(checkNode(root));
console.log(checkNode(root.childNodes[0]));
console.log(checkNode(root.childNodes[1]));
console.log(checkNode(root.childNodes[0].childNodes[0]));

Output

True
True
False
False

Time Complexity: O(N), where N is the number of nodes in the tree.
Auxillary Space: O(H), where H is the height of the tree (due to the recursion stack).