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# Find the Deepest Node in a Binary Tree

• Difficulty Level : Medium
• Last Updated : 28 Jul, 2021

Given a binary tree, find the deep­est node in it.
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```

Method 1: The idea is to do Inorder traversal of given binary tree. While doing Inorder traversal, we pass level of current node also. We keep track of maximum level seen so far and value of deepest node seen so far.

## C++

 `// A C++ program to find value of the deepest node``// in a given binary tree``#include ``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;``}` `// maxLevel : keeps track of maximum level seen so far.``// res :  Value of deepest node so far.``// level : Level of root``void` `find(Node *root, ``int` `level, ``int` `&maxLevel, ``int` `&res)``{``    ``if` `(root != NULL)``    ``{``        ``find(root->left, ++level, maxLevel, res);` `        ``// Update level and resue``        ``if` `(level > maxLevel)``        ``{``            ``res = root->data;``            ``maxLevel = level;``        ``}` `        ``find(root->right, level, maxLevel, res);``    ``}``}` `// Returns value of deepest node``int` `deepestNode(Node *root)``{``    ``// Initialize result and max level``    ``int` `res = -1;``    ``int` `maxLevel = -1;` `    ``// Updates value "res" and "maxLevel"``    ``// Note that res and maxLen are passed``    ``// by reference.``    ``find(root, 0, maxLevel, res);``    ``return` `res;``}` `// Driver program``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);``    ``cout << deepestNode(root);``    ``return` `0;``}`

## Java

 `// Java program to find value of the deepest node``// in a given binary tree``class` `GFG``{` `    ``// A tree node``    ``static` `class` `Node``    ``{` `        ``int` `data;``        ``Node left, right;` `        ``Node(``int` `key)``        ``{``            ``data = key;``            ``left = ``null``;``            ``right = ``null``;``        ``}``    ``}``    ``static` `int` `maxLevel = -``1``;``    ``static` `int` `res = -``1``;` `    ``// maxLevel : keeps track of maximum level seen so far.``    ``// res : Value of deepest node so far.``    ``// level : Level of root``    ``static` `void` `find(Node root, ``int` `level)``    ``{``        ``if` `(root != ``null``)``        ``{``            ``find(root.left, ++level);` `            ``// Update level and resue``            ``if` `(level > maxLevel)``            ``{``                ``res = root.data;``                ``maxLevel = level;``            ``}` `            ``find(root.right, level);``        ``}``    ``}` `    ``// Returns value of deepest node``    ``static` `int` `deepestNode(Node root)``    ``{``        ``// Initialize result and max level``        ``/* int res = -1;``        ``int maxLevel = -1; */` `        ``// Updates value "res" and "maxLevel"``        ``// Note that res and maxLen are passed``        ``// by reference.``        ``find(root, ``0``);``        ``return` `res;``    ``}` `    ``// Driver code``    ``public` `static` `void` `main(String[] args)``    ``{` `        ``Node root = ``new` `Node(``1``);``        ``root.left = ``new` `Node(``2``);``        ``root.right = ``new` `Node(``3``);``        ``root.left.left = ``new` `Node(``4``);``        ``root.right.left = ``new` `Node(``5``);``        ``root.right.right = ``new` `Node(``6``);``        ``root.right.left.right = ``new` `Node(``7``);``        ``root.right.right.right = ``new` `Node(``8``);``        ``root.right.left.right.left = ``new` `Node(``9``);``        ``System.out.println(deepestNode(root));``    ``}``}` `// This code is contributed by Princi Singh`

## Python3

 `"""Python3 program to find value of the``deepest node in a given binary tree"""` `# A Binary Tree Node``# Utility function to create a``# new tree node``class` `newNode:` `    ``# Constructor to create a newNode``    ``def` `__init__(``self``, data):``        ``self``.data``=` `data``        ``self``.left ``=` `None``        ``self``.right ``=` `None``        ``self``.visited ``=` `False` `# maxLevel : keeps track of maximum``# level seen so far.``# res : Value of deepest node so far.``# level : Level of root``def` `find(root, level, maxLevel, res):` `    ``if` `(root !``=` `None``):``        ``level ``+``=` `1``        ``find(root.left, level, maxLevel, res)` `        ``# Update level and resue``        ``if` `(level > maxLevel[``0``]):``        ` `            ``res[``0``] ``=` `root.data``            ``maxLevel[``0``] ``=` `level``        ` `        ``find(root.right, level, maxLevel, res)``        ` `# Returns value of deepest node``def` `deepestNode(root) :` `    ``# Initialize result and max level``    ``res ``=` `[``-``1``]``    ``maxLevel ``=` `[``-``1``]` `    ``# Updates value "res" and "maxLevel"``    ``# Note that res and maxLen are passed``    ``# by reference.``    ``find(root, ``0``, maxLevel, res)``    ``return` `res[``0``]``                        ` `# Driver Code``if` `__name__ ``=``=` `'__main__'``:``    ``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``)``    ``print``(deepestNode(root))` `# This code is contributed by``# SHUBHAMSINGH10`

## C#

 `// C# program to find value of the deepest node``// in a given binary tree``using` `System;``    ` `class` `GFG``{` `    ``// A tree node``    ``public` `class` `Node``    ``{` `        ``public` `int` `data;``        ``public` `Node left, right;` `        ``public` `Node(``int` `key)``        ``{``            ``data = key;``            ``left = ``null``;``            ``right = ``null``;``        ``}``    ``}``    ``static` `int` `maxLevel = -1;``    ``static` `int` `res = -1;` `    ``// maxLevel : keeps track of maximum level seen so far.``    ``// res : Value of deepest node so far.``    ``// level : Level of root``    ``static` `void` `find(Node root, ``int` `level)``    ``{``        ``if` `(root != ``null``)``        ``{``            ``find(root.left, ++level);` `            ``// Update level and resue``            ``if` `(level > maxLevel)``            ``{``                ``res = root.data;``                ``maxLevel = level;``            ``}` `            ``find(root.right, level);``        ``}``    ``}` `    ``// Returns value of deepest node``    ``static` `int` `deepestNode(Node root)``    ``{``        ``// Initialize result and max level``        ``/* int res = -1;``        ``int maxLevel = -1; */` `        ``// Updates value "res" and "maxLevel"``        ``// Note that res and maxLen are passed``        ``// by reference.``        ``find(root, 0);``        ``return` `res;``    ``}` `    ``// Driver code``    ``public` `static` `void` `Main(String[] args)``    ``{` `        ``Node root = ``new` `Node(1);``        ``root.left = ``new` `Node(2);``        ``root.right = ``new` `Node(3);``        ``root.left.left = ``new` `Node(4);``        ``root.right.left = ``new` `Node(5);``        ``root.right.right = ``new` `Node(6);``        ``root.right.left.right = ``new` `Node(7);``        ``root.right.right.right = ``new` `Node(8);``        ``root.right.left.right.left = ``new` `Node(9);``        ``Console.WriteLine(deepestNode(root));``    ``}``}` `// This code is contributed by 29AjayKumar`

## Javascript

 ``

Output:

` 9`

Time Complexity: O(n)
Method 2 : The idea here is to find the height of the given tree and then print the node at the bottom-most level.

## C++

 `// A C++ program to find value of the``// deepest node in a given binary tree``#include ``using` `namespace` `std;` `// A tree node with constructor``class` `Node``{``public``:``    ``int` `data;``    ``Node *left, *right;``    ` `    ``// constructor   ``    ``Node(``int` `key)``    ``{``        ``data = key;``        ``left = NULL;``        ``right = NULL;``    ``}``};` `// Utility function to find height``// of a tree, rooted at 'root'.``int` `height(Node* root)``{``  ``if``(!root) ``return` `0;``  ` `  ``int` `leftHt = height(root->left);``  ``int` `rightHt = height(root->right);``  ` `  ``return` `max(leftHt, rightHt) + 1;``}` `// levels : current Level``// Utility function to print all``// nodes at a given level.``void` `deepestNode(Node* root, ``int` `levels)``{``    ``if``(!root) ``return``;``    ` `    ``if``(levels == 1)``    ``cout << root->data;``    ` `    ``else` `if``(levels > 1)``    ``{``        ``deepestNode(root->left, levels - 1);``        ``deepestNode(root->right, levels - 1);``    ``}``}` `// Driver program``int` `main()``{``    ``Node* root = ``new` `Node(1);``    ``root->left = ``new` `Node(2);``    ``root->right = ``new` `Node(3);``    ``root->left->left = ``new` `Node(4);``    ``root->right->left = ``new` `Node(5);``    ``root->right->right = ``new` `Node(6);``    ``root->right->left->right = ``new` `Node(7);``    ``root->right->right->right = ``new` `Node(8);``    ``root->right->left->right->left = ``new` `Node(9);``    ` `    ``// Calculating height of tree``    ``int` `levels = height(root);``    ` `    ``// Printing the deepest node``    ``deepestNode(root, levels);``    ` `    ``return` `0;``}` `// This code is contributed by decode2207.`

## Java

 `// A Java program to find value of the``// deepest node in a given binary tree``class` `GFG``{``    ` `// A tree node with constructor``static` `class` `Node``{``    ``int` `data;``    ``Node left, right;``    ` `    ``// constructor``    ``Node(``int` `key)``    ``{``        ``data = key;``        ``left = ``null``;``        ``right = ``null``;``    ``}``};` `// Utility function to find height``// of a tree, rooted at 'root'.``static` `int` `height(Node root)``{``    ``if``(root == ``null``) ``return` `0``;``        ` `    ``int` `leftHt = height(root.left);``    ``int` `rightHt = height(root.right);``        ` `    ``return` `Math.max(leftHt, rightHt) + ``1``;``}` `// levels : current Level``// Utility function to print all``// nodes at a given level.``static` `void` `deepestNode(Node root,``                        ``int` `levels)``{``    ``if``(root == ``null``) ``return``;``    ` `    ``if``(levels == ``1``)``    ``System.out.print(root.data + ``" "``);``    ` `    ``else` `if``(levels > ``1``)``    ``{``        ``deepestNode(root.left, levels - ``1``);``        ``deepestNode(root.right, levels - ``1``);``    ``}``}` `// Driver Codede``public` `static` `void` `main(String args[])``{``    ``Node root = ``new` `Node(``1``);``    ``root.left = ``new` `Node(``2``);``    ``root.right = ``new` `Node(``3``);``    ``root.left.left = ``new` `Node(``4``);``    ``root.right.left = ``new` `Node(``5``);``    ``root.right.right = ``new` `Node(``6``);``    ``root.right.left.right = ``new` `Node(``7``);``    ``root.right.right.right = ``new` `Node(``8``);``    ``root.right.left.right.left = ``new` `Node(``9``);``    ` `    ``// Calculating height of tree``    ``int` `levels = height(root);``    ` `    ``// Printing the deepest node``    ``deepestNode(root, levels);``}``}` `// This code is contributed by Arnab Kundu`

## Python3

 `# A Python3 program to find value of the``# deepest node in a given binary tree``class` `new_Node:``    ``def` `__init__(``self``, key):``        ``self``.data ``=` `key``        ``self``.left ``=` `self``.right ``=` `None``        ` `# Utility function to find height``# of a tree, rooted at 'root'.``def` `height(root):``    ``if``(``not` `root):``        ``return` `0``    ` `    ``leftHt ``=` `height(root.left)``    ``rightHt ``=` `height(root.right)``    ` `    ``return` `max``(leftHt, rightHt) ``+` `1` `# levels : current Level``# Utility function to print all``# nodes at a given level.``def` `deepestNode(root, levels):``    ``if``(``not` `root):``        ``return``    ` `    ``if``(levels ``=``=` `1``):``        ``print``(root.data)``    ``elif``(levels > ``1``):``        ``deepestNode(root.left, levels ``-` `1``)``        ``deepestNode(root.right, levels ``-` `1``)` `# Driver Code``if` `__name__ ``=``=` `'__main__'``:` `    ``root ``=` `new_Node(``1``)``    ``root.left ``=` `new_Node(``2``)``    ``root.right ``=` `new_Node(``3``)``    ``root.left.left ``=` `new_Node(``4``)``    ``root.right.left ``=` `new_Node(``5``)``    ``root.right.right ``=` `new_Node(``6``)``    ``root.right.left.right ``=` `new_Node(``7``)``    ``root.right.right.right ``=` `new_Node(``8``)``    ``root.right.left.right.left ``=` `new_Node(``9``)``    ` `    ``# Calculating height of tree``    ``levels ``=` `height(root)``    ` `    ``# Printing the deepest node``    ``deepestNode(root, levels)` `# This code is contributed by PranchalK`

## C#

 `// C# program to find value of the``// deepest node in a given binary tree``using` `System;``    ` `class` `GFG``{``    ` `// A tree node with constructor``public` `class` `Node``{``    ``public` `int` `data;``    ``public` `Node left, right;``    ` `    ``// constructor``    ``public` `Node(``int` `key)``    ``{``        ``data = key;``        ``left = ``null``;``        ``right = ``null``;``    ``}``};` `// Utility function to find height``// of a tree, rooted at 'root'.``static` `int` `height(Node root)``{``    ``if``(root == ``null``) ``return` `0;``        ` `    ``int` `leftHt = height(root.left);``    ``int` `rightHt = height(root.right);``        ` `    ``return` `Math.Max(leftHt, rightHt) + 1;``}` `// levels : current Level``// Utility function to print all``// nodes at a given level.``static` `void` `deepestNode(Node root,``                        ``int` `levels)``{``    ``if``(root == ``null``) ``return``;``    ` `    ``if``(levels == 1)``    ``Console.Write(root.data + ``" "``);``    ` `    ``else` `if``(levels > 1)``    ``{``        ``deepestNode(root.left, levels - 1);``        ``deepestNode(root.right, levels - 1);``    ``}``}` `// Driver Code``public` `static` `void` `Main(String []args)``{``    ``Node root = ``new` `Node(1);``    ``root.left = ``new` `Node(2);``    ``root.right = ``new` `Node(3);``    ``root.left.left = ``new` `Node(4);``    ``root.right.left = ``new` `Node(5);``    ``root.right.right = ``new` `Node(6);``    ``root.right.left.right = ``new` `Node(7);``    ``root.right.right.right = ``new` `Node(8);``    ``root.right.left.right.left = ``new` `Node(9);``    ` `    ``// Calculating height of tree``    ``int` `levels = height(root);``    ` `    ``// Printing the deepest node``    ``deepestNode(root, levels);``}``}` `/* This code contributed by PrinciRaj1992 */`

## Javascript

 ``

Output:

`9`

Time Complexity: O(n)
Thanks to Parth Patekar for suggesting above method.

Method 3: The last node processed from the queue in level order is the deepest node in the binary tree.

## C++

 `// A C++ program to find value of the``// deepest node in a given binary tree``#include ``using` `namespace` `std;` `// A tree node with constructor``class` `Node``{``public``:``    ``int` `data;``    ``Node *left, *right;``     ` `    ``// constructor  ``    ``Node(``int` `key)``    ``{``        ``data = key;``        ``left = NULL;``        ``right = NULL;``    ``}``};` `// Function to return the deepest node``Node* deepestNode(Node* root)``{``    ``Node* tmp = NULL;``    ``if` `(root == NULL)``        ``return` `NULL;` `    ``// Creating a Queue``    ``queue q;``    ``q.push(root);` `    ``// Iterates until queue become empty``    ``while` `(q.size() > 0)``    ``{``        ``tmp = q.front();``        ``q.pop();``        ``if` `(tmp->left != NULL)``            ``q.push(tmp->left);``        ``if` `(tmp->right != NULL)``            ``q.push(tmp->right);``    ``}``    ``return` `tmp;``}``    ` `int` `main()``{``    ``Node* root = ``new` `Node(1);``    ``root->left = ``new` `Node(2);``    ``root->right = ``new` `Node(3);``    ``root->left->left = ``new` `Node(4);``    ``root->right->left = ``new` `Node(5);``    ``root->right->right = ``new` `Node(6);``    ``root->right->left->right = ``new` `Node(7);``    ``root->right->right->right = ``new` `Node(8);``    ``root->right->left->right->left = ``new` `Node(9);` `    ``Node* deepNode = deepestNode(root);``    ``cout << (deepNode->data);` `    ``return` `0;``}`

## Java

 `import` `java.util.*;` `// A Java program to find value of the``// deepest node in a given binary tree` `// A tree node with constructor``public` `class` `Node``{``    ``int` `data;``    ``Node left, right;` `    ``// constructor``    ``Node(``int` `key)``    ``{``        ``data = key;``        ``left = ``null``;``        ``right = ``null``;``    ``}``};` `class` `Gfg``{``  ` `    ``// Function to return the deepest node``    ``public` `static` `Node deepestNode(Node root)``    ``{``        ``Node tmp = ``null``;``        ``if` `(root == ``null``)``            ``return` `null``;` `        ``// Creating a Queue``        ``Queue q = ``new` `LinkedList();``        ``q.offer(root);` `        ``// Iterates until queue become empty``        ``while` `(!q.isEmpty())``        ``{``            ``tmp = q.poll();``            ``if` `(tmp.left != ``null``)``                ``q.offer(tmp.left);``            ``if` `(tmp.right != ``null``)``                ``q.offer(tmp.right);``        ``}``        ``return` `tmp;``    ``}` `    ``public` `static` `void` `main(String[] args)``    ``{` `        ``Node root = ``new` `Node(``1``);``        ``root.left = ``new` `Node(``2``);``        ``root.right = ``new` `Node(``3``);``        ``root.left.left = ``new` `Node(``4``);``        ``root.right.left = ``new` `Node(``5``);``        ``root.right.right = ``new` `Node(``6``);``        ``root.right.left.right = ``new` `Node(``7``);``        ``root.right.right.right = ``new` `Node(``8``);``        ``root.right.left.right.left = ``new` `Node(``9``);` `        ``Node deepNode = deepestNode(root);``        ``System.out.println(deepNode.data);``    ``}``}` `// Code is contributed by mahi_07`

## Python3

 `# A Python3 program to find value of the``# deepest node in a given binary tree by method 3``from` `collections ``import` `deque` `class` `new_Node:``    ``def` `__init__(``self``, key):``        ``self``.data ``=` `key``        ``self``.left ``=` `self``.right ``=` `None` `def` `deepestNode(root):``    ``if` `root ``=``=` `None``:``        ``return` `0``    ``q ``=` `deque()``    ``q.append(root)``    ``node ``=` `None``    ``while` `len``(q) !``=` `0``:``        ``node ``=` `q.popleft()``        ``if` `node.left ``is` `not` `None``:``            ``q.append(node.left)``        ``if` `node.right ``is` `not` `None``:``            ``q.append(node.right)``    ``return` `node.data`` ` `# Driver Code``if` `__name__ ``=``=` `'__main__'``:`` ` `    ``root ``=` `new_Node(``1``)``    ``root.left ``=` `new_Node(``2``)``    ``root.right ``=` `new_Node(``3``)``    ``root.left.left ``=` `new_Node(``4``)``    ``root.right.left ``=` `new_Node(``5``)``    ``root.right.right ``=` `new_Node(``6``)``    ``root.right.left.right ``=` `new_Node(``7``)``    ``root.right.right.right ``=` `new_Node(``8``)``    ``root.right.left.right.left ``=` `new_Node(``9``)``     ` `    ``# Calculating height of tree``    ``levels ``=` `deepestNode(root)``     ` `    ``# Printing the deepest node``    ``print``(levels)``    ` `# This code is contributed by Aprajita Chhawi`

## C#

 `// A C# program to find value of the``// deepest node in a given binary tree``using` `System;``using` `System.Collections.Generic;` `// A tree node with constructor``public` `class` `Node``{``  ``public``    ``int` `data;``  ``public``    ``Node left, right;` `  ``// constructor``  ``public``    ``Node(``int` `key)``  ``{``    ``data = key;``    ``left = ``null``;``    ``right = ``null``;``  ``}``};` `class` `Gfg``{` `  ``// Function to return the deepest node``  ``public` `static` `Node deepestNode(Node root)``  ``{``    ``Node tmp = ``null``;``    ``if` `(root == ``null``)``      ``return` `null``;` `    ``// Creating a Queue``    ``Queue q = ``new` `Queue();``    ``q.Enqueue(root);` `    ``// Iterates until queue become empty``    ``while` `(q.Count != 0)``    ``{``      ``tmp = q.Peek();``      ``q.Dequeue();``      ``if` `(tmp.left != ``null``)``        ``q.Enqueue(tmp.left);``      ``if` `(tmp.right != ``null``)``        ``q.Enqueue(tmp.right);``    ``}``    ``return` `tmp;``  ``}` `  ``// Driver code``  ``public` `static` `void` `Main(String[] args)``  ``{` `    ``Node root = ``new` `Node(1);``    ``root.left = ``new` `Node(2);``    ``root.right = ``new` `Node(3);``    ``root.left.left = ``new` `Node(4);``    ``root.right.left = ``new` `Node(5);``    ``root.right.right = ``new` `Node(6);``    ``root.right.left.right = ``new` `Node(7);``    ``root.right.right.right = ``new` `Node(8);``    ``root.right.left.right.left = ``new` `Node(9);` `    ``Node deepNode = deepestNode(root);``    ``Console.WriteLine(deepNode.data);``  ``}``}` `// This code is contributed by gauravrajput1`

## Javascript

 ``

Output
`9`

Time Complexity: O(n)

Space Complexity: O(n)

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