Find the Deepest Node in a Binary Tree Using Queue STL – SET 2
Given a binary tree. The task is to find the value of the deepest node in the given binary tree.
Examples:
Input: Root of below tree 1 / \ 2 3 / \ / \ 4 5 6 7 \ 8 Output: 8 Input: Root of below tree 1 / \ 2 3 / 6 Output: 6
Approach: We have already discussed the two different ways to find the deepest node in a binary tree in this post. Here, we will find the deepest node in the tree using a queue data structure. We will first push the root into the queue and then we will push its child nodes after removing the parent node from the queue. We will continue this process until the queue is empty. The last node in the queue is the deepest node of the binary tree.
Below is the implementation of the above approach as follows:
C++
// C++ program to find the value of the // deepest node in a given binary tree. #include <bits/stdc++.h> using namespace std; // A tree node struct Node { int data; struct Node *left, *right; }; // Utility function to create a new node Node* newNode( int data) { Node* temp = new Node; temp->data = data; temp->left = temp->right = NULL; return temp; } // Function to find the deepest node in a tree int findDeepest( struct Node* root) { struct Node* temp = NULL; queue<Node*> q; if (root == NULL) return 0; // Push the root node q.push(root); while (!q.empty()) { temp = q.front(); q.pop(); // Push left child if (temp->left) q.push(temp->left); // Push right child if (temp->right) q.push(temp->right); } // Return the deepest node's value return temp->data; } // Driver code int main() { Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->right->left = newNode(5); root->right->right = newNode(6); root->right->left->right = newNode(7); root->right->right->right = newNode(8); root->right->left->right->left = newNode(9); // Function call cout << findDeepest(root); return 0; } |
Java
// Java program to find the value of the // deepest node in a given binary tree. import java.util.*; class GFG { // A tree node static class Node { int data; Node left , right; }; // Utility function to create a new node static Node newNode( int data) { Node temp = new Node(); temp.data = data; temp.left = temp.right = null ; return temp; } // Function to find the deepest node in a tree static int findDeepest(Node root) { Node temp = null ; Queue <Node> q = new LinkedList<Node>(); if (root == null ) return 0 ; // Push the root node q.add(root); while (!q.isEmpty()) { temp = q.peek(); q.remove(); // Push left child if (temp.left!= null ) q.add(temp.left); // Push right child if (temp.right!= null ) q.add(temp.right); } // Return the deepest node's value return temp.data; } // Driver code public static void main(String[] args) { Node root = newNode( 1 ); root.left = newNode( 2 ); root.right = newNode( 3 ); root.left.left = newNode( 4 ); root.right.left = newNode( 5 ); root.right.right = newNode( 6 ); root.right.left.right = newNode( 7 ); root.right.right.right = newNode( 8 ); root.right.left.right.left = newNode( 9 ); // Function call System.out.println(findDeepest(root)); } } // This code is contributed by 29AjayKumar |
Python3
# Python3 program to find the value of the # deepest node in a given binary tree. from collections import deque # A tree node class Node: def __init__( self , data): self .data = data self .left = None self .right = None # Function to find the deepest node in a tree def findDeepest(root: Node) - > int : temp = None q = deque() if (root = = None ): return 0 # Push the root node q.append(root) while q: temp = q[ 0 ] q.popleft() # Push left child if (temp.left): q.append(temp.left) # Append right child if (temp.right): q.append(temp.right) # Return the deepest node's value return temp.data # Driver code if __name__ = = "__main__" : root = Node( 1 ) root.left = Node( 2 ) root.right = Node( 3 ) root.left.left = Node( 4 ) root.right.left = Node( 5 ) root.right.right = Node( 6 ) root.right.left.right = Node( 7 ) root.right.right.right = Node( 8 ) root.right.left.right.left = Node( 9 ) # Function call print (findDeepest(root)) # This code is contributed by sanjeev2552 |
C#
// C# program to find the value of the // deepest node in a given binary tree. using System; using System.Collections.Generic; class GFG { // A tree node public class Node { public int data; public Node left , right; }; // Utility function to create a new node static Node newNode( int data) { Node temp = new Node(); temp.data = data; temp.left = temp.right = null ; return temp; } // Function to find the deepest node in a tree static int findDeepest(Node root) { Node temp = null ; Queue <Node> q = new Queue <Node>(); if (root == null ) return 0; // Push the root node q.Enqueue(root); while (q.Count != 0) { temp = q.Peek(); q.Dequeue(); // Push left child if (temp.left != null ) q.Enqueue(temp.left); // Push right child if (temp.right != null ) q.Enqueue(temp.right); } // Return the deepest node's value return temp.data; } // Driver code public static void Main(String[] args) { Node root = newNode(1); root.left = newNode(2); root.right = newNode(3); root.left.left = newNode(4); root.right.left = newNode(5); root.right.right = newNode(6); root.right.left.right = newNode(7); root.right.right.right = newNode(8); root.right.left.right.left = newNode(9); // Function call Console.WriteLine(findDeepest(root)); } } // This code is contributed by PrinciRaj1992 |
Javascript
<script> // Javascript program to find the value of the // deepest node in a given binary tree. // A tree node class Node { constructor() { this .data = 0; this .left = null ; this .right = null ; } }; // Utility function to create a new node function newNode(data) { var temp = new Node(); temp.data = data; temp.left = temp.right = null ; return temp; } // Function to find the deepest node in a tree function findDeepest(root) { var temp = null ; var q = []; if (root == null ) return 0; // Push the root node q.push(root); while (q.length != 0) { temp = q[0]; q.shift(); // Push left child if (temp.left != null ) q.push(temp.left); // Push right child if (temp.right != null ) q.push(temp.right); } // Return the deepest node's value return temp.data; } // Driver code var root = newNode(1); root.left = newNode(2); root.right = newNode(3); root.left.left = newNode(4); root.right.left = newNode(5); root.right.right = newNode(6); root.right.left.right = newNode(7); root.right.right.right = newNode(8); root.right.left.right.left = newNode(9); // Function call document.write(findDeepest(root)); // This code is contributed by noob2000 </script> |
Output
9
Time Complexity: O(N)
Auxiliary Space: O(N) because using queue “q”