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Print all K-sum levels in a Binary Tree

The problem is to print all the levels in a binary tree where the sum of the nodes' values in that level is equal to a given value K.

Problem Statement

Given a binary tree and an integer K, the task is to print all the levels in the binary tree where the sum of the nodes' values in that level is equal to K.

Example Scenario

Consider the binary tree shown below:

           10
         /   \
        2     3
       /     / \
      4     1   5
     /  \    \    \
    7    3    6   11
        /  \     /
       5    8   -3
           / \    
         -1   11

For this tree, if K is 10, then the levels with the sum of nodes' values equal to 10 are:

  • Level 1: 10
  • Level 2: 4 1 5
  • Level 3: 5 8 -3
  • Level 4: -1 11

Idea to Solve the Problem

We can use a BFS (Breadth-First Search) approach to traverse the binary tree level by level and calculate the sum of nodes' values in each level. We'll keep track of the level and sum for each node in a queue. As we traverse each level, we'll check if the sum equals K and print the nodes' values if it does.

Pseudocode

void level_sum(struct Node *root, int k)
{
    // Check if the root is NULL
    if (root == NULL)
    {
        printf("Empty Tree\n");
        return;
    }
    
    // Initialize a queue
    // Enqueue the root node with level 1
    // Initialize level, sum, and status
    
    while (queue is not empty)
    {
        // Traverse the current level
        // Calculate sum of nodes' values
        
        // If sum equals K, print the nodes' values
        
        // Dequeue nodes from the queue
    }
}

Algorithm Explanation

  1. Implement the level_sum function that takes the root of the binary tree and integer K as input.
  2. Check if the root is NULL, if so, print "Empty Tree" and return.
  3. Initialize a queue data structure for the BFS traversal.
  4. Enqueue the root node along with its level (starting from 1).
  5. Start a loop that continues until the queue is empty.
  6. Inside the loop, traverse the current level and calculate the sum of nodes' values in that level.
  7. If the sum equals K, set a status flag to 1.
  8. Traverse the queue again and print the nodes' values if the status flag is set to 1.
  9. Dequeue nodes from the queue as you process them.
  10. This process ensures that all levels are traversed, and the nodes with sum equal to K are printed.

Code Solution

// C program
// Print all K-sum levels in a Binary Tree
#include <stdio.h>

#include <stdlib.h>

//Node of binary tree
struct Node
{
	int data;
	struct Node *left, *right;
};
struct MyQueue
{
	int level;
	struct Node *element;
	struct MyQueue *next;
};
//Create a binary tree nodes and node fields (data,pointer) 
//And returning the reference of newly nodes
struct Node *insert(int data)
{
	//create dynamic memory to new binary tree node
	struct Node *new_node = (struct Node *) malloc(sizeof(struct Node));
	if (new_node != NULL)
	{
		//Set node value
		new_node->data = data;
		new_node->left = NULL;
		new_node->right = NULL;
	}
	else
	{
		printf("Memory Overflow\n");
	}
	//return reference
	return new_node;
}
//Create a queue node and returns this node
struct MyQueue *enqueue(struct Node *tree_node)
{
	//Make a new Queue node
	struct MyQueue *new_node = (struct MyQueue *) malloc(sizeof(struct MyQueue));
	if (new_node != NULL)
	{
		//Set node values
		new_node->element = tree_node;
		new_node->next = NULL;
	}
	else
	{
		printf("Memory Overflow\n");
	}
	return new_node;
}
//Remove a queue elements
void dequeue(struct MyQueue **front)
{
	if ( *front != NULL)
	{
		struct MyQueue *remove = *front;
		//Visit to next node
		*front = remove->next;
		remove->element = NULL;
		remove->next = NULL;
		//free node
		free(remove);
		remove = NULL;
	}
}
//Print all levels which sum is equal to given value
void level_sum(struct Node *root, int k)
{
	if (root != NULL)
	{
		//make a queue pointers
		struct MyQueue *front = NULL, *tail = NULL;
		struct MyQueue *temp = NULL;
		//Get first node of tree
		front = enqueue(root);
		//Start level of first node is one
		front->level = 1;
		//Set tail node to first node
		tail = front;
		struct Node *node = root;
		// Start to first node
		temp = front;
		// Get level elements into a queue
		while (temp != NULL)
		{
			//Tree node
			node = temp->element;
			if (node->left != NULL)
			{
				//Add new left child node
				tail->next = enqueue(node->left);
				tail->next->level = temp->level + 1;
				tail = tail->next;
			}
			if (node->right != NULL)
			{
				//Add new right child node
				tail->next = enqueue(node->right);
				tail->next->level = temp->level + 1;
				tail = tail->next;
			}
			//Visit to next node queue
			temp = temp->next;
		}
		//result node indicator
		int status = 0;
		int level = 0;
		int sum = 0;
		while (front != NULL)
		{
			level = front->level;
			status = 0;
			sum = 0;
			temp = front;
			//Calculate the sum of level node
			while (temp != NULL && temp->level == level)
			{
				sum += temp->element->data;
				temp = temp->next;
			}
			if (sum == k)
			{
				//When k sum exist
				status = 1;
				printf(" [");
			}
			// Traversal the tree level
			while (front != NULL && front->level == level)
			{
				if (status == 1)
				{
					//When sum is equal to k
					printf(" %d", front->element->data);
				}
				//remove  a queue node
				dequeue( &front);
			}
			if (status == 1)
			{
				printf(" ]\n");
			}
		}
		tail = NULL;
	}
	else
	{
		printf("Empty Tree\n");
	}
}
int main()
{
	struct Node *root = NULL;
	/*
	Construct Binary Tree
	-----------------------
	           10
	         /   \
	        2     3
	       /     / \
	      4     1   5
	     /  \    \    \
	    7    3    6   11
	        /  \     /
	       5    8   -3
	           / \    
	         -1   11

	-----------------------
	*/
	//Add node
	root = insert(10);
	root->left = insert(2);
	root->right = insert(3);
	root->right->right = insert(5);
	root->right->left = insert(1);
	root->left->left = insert(4);
	root->left->left->left = insert(7);
	root->left->left->right = insert(3);
	root->right->left->right = insert(6);
	root->right->right->right = insert(11);
	root->right->right->right->left = insert(-3);
	root->left->left->right->left = insert(5);
	root->left->left->right->right = insert(8);
	root->left->left->right->right->left = insert(-1);
	root->left->left->right->right->right = insert(11);
	level_sum(root, 10);
	return 0;
}

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
/* 
  Java program 
  Print all K-sum levels in a Binary Tree
*/
//Binary Tree node
class TreeNode
{
	public int data;
	public TreeNode left;
	public TreeNode right;
	public TreeNode(int data)
	{
		//set node value
		this.data = data;
		this.left = null;
		this.right = null;
	}
}
// Queue Node
class QueueNode
{
	public TreeNode element;
	public QueueNode next;
	public int level;
	public QueueNode(TreeNode element, int level)
	{
		this.element = element;
		this.next = null;
		this.level = level;
	}
}
//Define custom queue class
class MyQueue
{
	public QueueNode front;
	public QueueNode tail;
	public MyQueue()
	{
		this.front = null;
		this.tail = null;
	}
	//Add a new node at last of queue
	public void enqueue(TreeNode element, int level)
	{
		QueueNode new_node = new QueueNode(element, level);
		if (this.front == null)
		{
			//When first node of queue
			this.front = new_node;
		}
		else
		{
			//Add node at last position
			this.tail.next = new_node;
		}
		this.tail = new_node;
	}
	//Delete first node of queue
	public void dequeue()
	{
		if (this.front != null)
		{
			if (this.tail == this.front)
			{
				this.tail = null;
				this.front = null;
			}
			else
			{
				this.front = this.front.next;
			}
		}
	}
	public boolean is_empty()
	{
		if (this.front == null)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}
class BinaryTree
{
	public TreeNode root;
	public BinaryTree()
	{
		// Set initial tree root to null
		this.root = null;
	}
	public boolean is_k_level_sum(MyQueue queue, int level, int k)
	{
		if (queue.is_empty() == true)
		{
			return false;
		}
		int sum = 0;
		QueueNode temp = queue.front;
		//Count number of nodes in given level
		while (temp != null && temp.level == level)
		{
			sum += temp.element.data;
			temp = temp.next;
		}
		if (sum == k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	public void level_sum(int k)
	{
		if (this.root == null)
		{
			System.out.print("\n Empty Binary Tree \n");
		}
		else
		{
			//Get top node in tree
			TreeNode node = this.root;
			//Create a Queue
			MyQueue queue = new MyQueue();
			//Add first node at the level of one
			queue.enqueue(node, 1);
			QueueNode temp = queue.front;
			int level = 0;
			//Add tree level
			while (temp != null)
			{
				node = temp.element;
				level = temp.level;
				if (node.left != null)
				{
					//Add left node
					queue.enqueue(node.left, level + 1);
				}
				if (node.right != null)
				{
					//Add right node
					queue.enqueue(node.right, level + 1);
				}
				temp = temp.next;
			}
			boolean status = false;
			level = 0;
			while (queue.is_empty() == false)
			{
				level = queue.front.level;
				status = is_k_level_sum(queue, level, k);
				if (status == true)
				{
					System.out.print(" [");
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it's removing current level nodes
				while (queue.is_empty() == false && queue.front.level == level)
				{
					if (status == true)
					{
						//When sum exist
						System.out.print(" " + queue.front.element.data);
					}
					//remove  a queue node
					queue.dequeue();
				}
				if (status == true)
				{
					System.out.print(" ]\n");
				}
			}
		}
	}
	public static void main(String[] args)
	{
		//Object of Binary Tree
		BinaryTree tree = new BinaryTree();
		/*  
		Construct Binary Tree
		-----------------------
		           10
		         /   \
		        2     3
		       /     / \
		      4     1   5
		     /  \    \    \
		    7    3    6   11
		        /  \     /
		       5    8   -3
		           / \    
		         -1   11

		-----------------------
		*/
		//Add node
		tree.root = new TreeNode(10);
		tree.root.left = new TreeNode(2);
		tree.root.right = new TreeNode(3);
		tree.root.right.right = new TreeNode(5);
		tree.root.right.left = new TreeNode(1);
		tree.root.left.left = new TreeNode(4);
		tree.root.left.left.left = new TreeNode(7);
		tree.root.left.left.right = new TreeNode(3);
		tree.root.right.left.right = new TreeNode(6);
		tree.root.right.right.right = new TreeNode(11);
		tree.root.right.right.right.left = new TreeNode(-3);
		tree.root.left.left.right.left = new TreeNode(5);
		tree.root.left.left.right.right = new TreeNode(8);
		tree.root.left.left.right.right.left = new TreeNode(-1);
		tree.root.left.left.right.right.right = new TreeNode(11);
		tree.level_sum(10);
	}
}

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
//Include header file
#include <iostream>
using namespace std;

/*
  C++ program 
  Print all K-sum levels in a Binary Tree
*/

//Binary Tree node
class TreeNode
{
	public: 
    int data;
	TreeNode *left;
	TreeNode *right;
	TreeNode(int data)
	{
		//set node value
		this->data = data;
		this->left = NULL;
		this->right = NULL;
	}
};
// Queue Node
class QueueNode
{
	public: TreeNode *element;
	QueueNode *next;
	int level;
	QueueNode(TreeNode *element, int level)
	{
		this->element = element;
		this->next = NULL;
		this->level = level;
	}
};
//Define custom queue class
class MyQueue
{
	public: QueueNode *front;
	QueueNode *tail;
	MyQueue()
	{
		this->front = NULL;
		this->tail = NULL;
	}
	//Add a new node at last of queue
	void enqueue(TreeNode *element, int level)
	{
		QueueNode *new_node = new QueueNode(element, level);
		if (this->front == NULL)
		{
			//When first node of queue
			this->front = new_node;
		}
		else
		{
			//Add node at last position
			this->tail->next = new_node;
		}
		this->tail = new_node;
	}
	//Delete first node of queue
	void dequeue()
	{
		if (this->front != NULL)
		{
          	QueueNode *temp = this->front;
			if (this->tail == this->front)
			{
				this->tail = NULL;
				this->front = NULL;
			}
			else
			{
				this->front = this->front->next;
			}
            delete temp;
		}
	}
	bool is_empty()
	{
		if (this->front == NULL)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
};
class BinaryTree
{
	public: TreeNode *root;
	BinaryTree()
	{
		// Set initial tree root to null
		this->root = NULL;
	}
	bool is_k_level_sum(MyQueue queue, int level, int k)
	{
		if (queue.is_empty() == true)
		{
			return false;
		}
		int sum = 0;
		QueueNode *temp = queue.front;
		//Count number of nodes in given level
		while (temp != NULL && temp->level == level)
		{
			sum += temp->element->data;
			temp = temp->next;
		}
		if (sum == k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	void level_sum(int k)
	{
		if (this->root == NULL)
		{
			cout << "\n Empty Binary Tree \n";
		}
		else
		{
			//Get top node in tree
			TreeNode *node = this->root;
			//Create a Queue
			MyQueue queue = MyQueue();
			//Add first node at the level of one
			queue.enqueue(node, 1);
			QueueNode *temp = queue.front;
			int level = 0;
			//Add tree level
			while (temp != NULL)
			{
				node = temp->element;
				level = temp->level;
				if (node->left != NULL)
				{
					//Add left node
					queue.enqueue(node->left, level + 1);
				}
				if (node->right != NULL)
				{
					//Add right node
					queue.enqueue(node->right, level + 1);
				}
				temp = temp->next;
			}
			bool status = false;
			level = 0;
			while (queue.is_empty() == false)
			{
				level = queue.front->level;
				status = this->is_k_level_sum(queue, level, k);
				if (status == true)
				{
					cout << " [";
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it's removing current level nodes
				while (queue.is_empty() == false && queue.front->level == level)
				{
					if (status == true)
					{
						//When sum exist
						cout << " " << queue.front->element->data;
					}
					//remove  a queue node
					queue.dequeue();
				}
				if (status == true)
				{
					cout << " ]\n";
				}
			}
		}
	}
};
int main()
{
	//Object of Binary Tree
	BinaryTree tree = BinaryTree();
	tree.root = new TreeNode(10);
	tree.root->left = new TreeNode(2);
	tree.root->right = new TreeNode(3);
	tree.root->right->right = new TreeNode(5);
	tree.root->right->left = new TreeNode(1);
	tree.root->left->left = new TreeNode(4);
	tree.root->left->left->left = new TreeNode(7);
	tree.root->left->left->right = new TreeNode(3);
	tree.root->right->left->right = new TreeNode(6);
	tree.root->right->right->right = new TreeNode(11);
	tree.root->right->right->right->left = new TreeNode(-3);
	tree.root->left->left->right->left = new TreeNode(5);
	tree.root->left->left->right->right = new TreeNode(8);
	tree.root->left->left->right->right->left = new TreeNode(-1);
	tree.root->left->left->right->right->right = new TreeNode(11);
	tree.level_sum(10);
	return 0;
}

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
//Include namespace system
using System;

/* 
  C# program 
  Print all K-sum levels in a Binary Tree
*/

//Binary Tree node
class TreeNode
{
	public int data;
	public TreeNode left;
	public TreeNode right;
	public TreeNode(int data)
	{
		//set node value
		this.data = data;
		this.left = null;
		this.right = null;
	}
}
// Queue Node
class QueueNode
{
	public TreeNode element;
	public QueueNode next;
	public int level;
	public QueueNode(TreeNode element, int level)
	{
		this.element = element;
		this.next = null;
		this.level = level;
	}
}
//Define custom queue class
class MyQueue
{
	public QueueNode front;
	public QueueNode tail;
	public MyQueue()
	{
		this.front = null;
		this.tail = null;
	}
	//Add a new node at last of queue
	public void enqueue(TreeNode element, int level)
	{
		QueueNode new_node = new QueueNode(element, level);
		if (this.front == null)
		{
			//When first node of queue
			this.front = new_node;
		}
		else
		{
			//Add node at last position
			this.tail.next = new_node;
		}
		this.tail = new_node;
	}
	//Delete first node of queue
	public void dequeue()
	{
		if (this.front != null)
		{
			if (this.tail == this.front)
			{
				this.tail = null;
				this.front = null;
			}
			else
			{
				this.front = this.front.next;
			}
		}
	}
	public Boolean is_empty()
	{
		if (this.front == null)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}
class BinaryTree
{
	public TreeNode root;
	public BinaryTree()
	{
		// Set initial tree root to null
		this.root = null;
	}
	public Boolean is_k_level_sum(MyQueue queue, int level, int k)
	{
		if (queue.is_empty() == true)
		{
			return false;
		}
		int sum = 0;
		QueueNode temp = queue.front;
		//Count number of nodes in given level
		while (temp != null && temp.level == level)
		{
			sum += temp.element.data;
			temp = temp.next;
		}
		if (sum == k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	public void level_sum(int k)
	{
		if (this.root == null)
		{
			Console.Write("\n Empty Binary Tree \n");
		}
		else
		{
			//Get top node in tree
			TreeNode node = this.root;
			//Create a Queue
			MyQueue queue = new MyQueue();
			//Add first node at the level of one
			queue.enqueue(node, 1);
			QueueNode temp = queue.front;
			int level = 0;
			//Add tree level
			while (temp != null)
			{
				node = temp.element;
				level = temp.level;
				if (node.left != null)
				{
					//Add left node
					queue.enqueue(node.left, level + 1);
				}
				if (node.right != null)
				{
					//Add right node
					queue.enqueue(node.right, level + 1);
				}
				temp = temp.next;
			}
			Boolean status = false;
			level = 0;
			while (queue.is_empty() == false)
			{
				level = queue.front.level;
				status = is_k_level_sum(queue, level, k);
				if (status == true)
				{
					Console.Write(" [");
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it's removing current level nodes
				while (queue.is_empty() == false && queue.front.level == level)
				{
					if (status == true)
					{
						//When sum exist
						Console.Write(" " + queue.front.element.data);
					}
					//remove  a queue node
					queue.dequeue();
				}
				if (status == true)
				{
					Console.Write(" ]\n");
				}
			}
		}
	}
	public static void Main(String[] args)
	{
		//Object of Binary Tree
		BinaryTree tree = new BinaryTree();
		tree.root = new TreeNode(10);
		tree.root.left = new TreeNode(2);
		tree.root.right = new TreeNode(3);
		tree.root.right.right = new TreeNode(5);
		tree.root.right.left = new TreeNode(1);
		tree.root.left.left = new TreeNode(4);
		tree.root.left.left.left = new TreeNode(7);
		tree.root.left.left.right = new TreeNode(3);
		tree.root.right.left.right = new TreeNode(6);
		tree.root.right.right.right = new TreeNode(11);
		tree.root.right.right.right.left = new TreeNode(-3);
		tree.root.left.left.right.left = new TreeNode(5);
		tree.root.left.left.right.right = new TreeNode(8);
		tree.root.left.left.right.right.left = new TreeNode(-1);
		tree.root.left.left.right.right.right = new TreeNode(11);
		tree.level_sum(10);
	}
}

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
<?php
/* 
  Php program 
  Print all K-sum levels in a Binary Tree
*/
//Binary Tree node
class TreeNode
{
	public $data;
	public $left;
	public $right;

	function __construct($data)
	{
		//set node value
		$this->data = $data;
		$this->left = null;
		$this->right = null;
	}
}
// Queue Node
class QueueNode
{
	public $element;
	public $next;
	public $level;

	function __construct($element, $level)
	{
		$this->element = $element;
		$this->next = null;
		$this->level = $level;
	}
}
//Define custom queue class
class MyQueue
{
	public $front;
	public $tail;

	function __construct()
	{
		$this->front = null;
		$this->tail = null;
	}
	//Add a new node at last of queue
	public	function enqueue($element, $level)
	{
		$new_node = new QueueNode($element, $level);
		if ($this->front == null)
		{
			//When first node of queue
			$this->front = $new_node;
		}
		else
		{
			//Add node at last position
			$this->tail->next = $new_node;
		}
		$this->tail = $new_node;
	}
	//Delete first node of queue
	public	function dequeue()
	{
		if ($this->front != null)
		{
			if ($this->tail == $this->front)
			{
				$this->tail = null;
				$this->front = null;
			}
			else
			{
				$this->front = $this->front->next;
			}
		}
	}
	public	function is_empty()
	{
		if ($this->front == null)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}
class BinaryTree
{
	public $root;

	function __construct()
	{
		// Set initial tree root to null
		$this->root = null;
	}
	public	function is_k_level_sum($queue, $level, $k)
	{
		if ($queue->is_empty() == true)
		{
			return false;
		}
		$sum = 0;
		$temp = $queue->front;
		//Count number of nodes in given level
		while ($temp != null && $temp->level == $level)
		{
			$sum += $temp->element->data;
			$temp = $temp->next;
		}
		if ($sum == $k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	public	function level_sum($k)
	{
		if ($this->root == null)
		{
			echo "\n Empty Binary Tree \n";
		}
		else
		{
			//Get top node in tree
			$node = $this->root;
			//Create a Queue
			$queue = new MyQueue();
			//Add first node at the level of one
			$queue->enqueue($node, 1);
			$temp = $queue->front;
			$level = 0;
			//Add tree level
			while ($temp != null)
			{
				$node = $temp->element;
				$level = $temp->level;
				if ($node->left != null)
				{
					//Add left node
					$queue->enqueue($node->left, $level + 1);
				}
				if ($node->right != null)
				{
					//Add right node
					$queue->enqueue($node->right, $level + 1);
				}
				$temp = $temp->next;
			}
			$status = false;
			$level = 0;
			while ($queue->is_empty() == false)
			{
				$level = $queue->front->level;
				$status = $this->is_k_level_sum($queue, $level, $k);
				if ($status == true)
				{
					echo " [";
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it's removing current level nodes
				while ($queue->is_empty() == false && $queue->front->level == $level)
				{
					if ($status == true)
					{
						//When sum exist
						echo " ". $queue->front->element->data;
					}
					//remove  a queue node
					$queue->dequeue();
				}
				if ($status == true)
				{
					echo " ]\n";
				}
			}
		}
	}
}

function main()
{
	//Object of Binary Tree
	$tree = new BinaryTree();
	/*  
			Construct Binary Tree
			-----------------------
			           10
			         /   \
			        2     3
			       /     / \
			      4     1   5
			     /  \    \    \
			    7    3    6   11
			        /  \     /
			       5    8   -3
			           / \    
			         -1   11

			-----------------------
			*/
	//Add node
	$tree->root = new TreeNode(10);
	$tree->root->left = new TreeNode(2);
	$tree->root->right = new TreeNode(3);
	$tree->root->right->right = new TreeNode(5);
	$tree->root->right->left = new TreeNode(1);
	$tree->root->left->left = new TreeNode(4);
	$tree->root->left->left->left = new TreeNode(7);
	$tree->root->left->left->right = new TreeNode(3);
	$tree->root->right->left->right = new TreeNode(6);
	$tree->root->right->right->right = new TreeNode(11);
	$tree->root->right->right->right->left = new TreeNode(-3);
	$tree->root->left->left->right->left = new TreeNode(5);
	$tree->root->left->left->right->right = new TreeNode(8);
	$tree->root->left->left->right->right->left = new TreeNode(-1);
	$tree->root->left->left->right->right->right = new TreeNode(11);
	$tree->level_sum(10);
}
main();

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
/* 
  Node Js program 
  Print all K-sum levels in a Binary Tree
*/
//Binary Tree node
class TreeNode
{
	constructor(data)
	{
		//set node value
		this.data = data;
		this.left = null;
		this.right = null;
	}
}
// Queue Node
class QueueNode
{
	constructor(element, level)
	{
		this.element = element;
		this.next = null;
		this.level = level;
	}
}
//Define custom queue class
class MyQueue
{
	constructor()
	{
		this.front = null;
		this.tail = null;
	}
	//Add a new node at last of queue
	enqueue(element, level)
	{
		var new_node = new QueueNode(element, level);
		if (this.front == null)
		{
			//When first node of queue
			this.front = new_node;
		}
		else
		{
			//Add node at last position
			this.tail.next = new_node;
		}
		this.tail = new_node;
	}
	//Delete first node of queue
	dequeue()
	{
		if (this.front != null)
		{
			if (this.tail == this.front)
			{
				this.tail = null;
				this.front = null;
			}
			else
			{
				this.front = this.front.next;
			}
		}
	}
	is_empty()
	{
		if (this.front == null)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}
class BinaryTree
{
	constructor()
	{
		// Set initial tree root to null
		this.root = null;
	}
	is_k_level_sum(queue, level, k)
	{
		if (queue.is_empty() == true)
		{
			return false;
		}
		var sum = 0;
		var temp = queue.front;
		//Count number of nodes in given level
		while (temp != null && temp.level == level)
		{
			sum += temp.element.data;
			temp = temp.next;
		}
		if (sum == k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	level_sum(k)
	{
		if (this.root == null)
		{
			process.stdout.write("\n Empty Binary Tree \n");
		}
		else
		{
			//Get top node in tree
			var node = this.root;
			//Create a Queue
			var queue = new MyQueue();
			//Add first node at the level of one
			queue.enqueue(node, 1);
			var temp = queue.front;
			var level = 0;
			//Add tree level
			while (temp != null)
			{
				node = temp.element;
				level = temp.level;
				if (node.left != null)
				{
					//Add left node
					queue.enqueue(node.left, level + 1);
				}
				if (node.right != null)
				{
					//Add right node
					queue.enqueue(node.right, level + 1);
				}
				temp = temp.next;
			}
			var status = false;
			level = 0;
			while (queue.is_empty() == false)
			{
				level = queue.front.level;
				status = this.is_k_level_sum(queue, level, k);
				if (status == true)
				{
					process.stdout.write(" [");
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it's removing current level nodes
				while (queue.is_empty() == false && queue.front.level == level)
				{
					if (status == true)
					{
						//When sum exist
						process.stdout.write(" " + queue.front.element.data);
					}
					//remove  a queue node
					queue.dequeue();
				}
				if (status == true)
				{
					process.stdout.write(" ]\n");
				}
			}
		}
	}
}

function main()
{
	//Object of Binary Tree
	var tree = new BinaryTree();
	/*  
			Construct Binary Tree
			-----------------------
			           10
			         /   \
			        2     3
			       /     / \
			      4     1   5
			     /  \    \    \
			    7    3    6   11
			        /  \     /
			       5    8   -3
			           / \    
			         -1   11

			-----------------------
			*/
	//Add node
	tree.root = new TreeNode(10);
	tree.root.left = new TreeNode(2);
	tree.root.right = new TreeNode(3);
	tree.root.right.right = new TreeNode(5);
	tree.root.right.left = new TreeNode(1);
	tree.root.left.left = new TreeNode(4);
	tree.root.left.left.left = new TreeNode(7);
	tree.root.left.left.right = new TreeNode(3);
	tree.root.right.left.right = new TreeNode(6);
	tree.root.right.right.right = new TreeNode(11);
	tree.root.right.right.right.left = new TreeNode(-3);
	tree.root.left.left.right.left = new TreeNode(5);
	tree.root.left.left.right.right = new TreeNode(8);
	tree.root.left.left.right.right.left = new TreeNode(-1);
	tree.root.left.left.right.right.right = new TreeNode(11);
	tree.level_sum(10);
}
main();

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
#   Python 3 program 
#   Print all K-sum levels in a Binary Tree

# Binary Tree node
class TreeNode :
	
	def __init__(self, data) :
		# set node value
		self.data = data
		self.left = None
		self.right = None
	

#  Queue Node
class QueueNode :
	
	def __init__(self, element, level) :
		self.element = element
		self.next = None
		self.level = level
	

# Define custom queue class
class MyQueue :
	
	def __init__(self) :
		self.front = None
		self.tail = None
	
	# Add a new node at last of queue
	def enqueue(self, element, level) :
		new_node = QueueNode(element, level)
		if (self.front == None) :
			# When first node of queue
			self.front = new_node
		else :
			# Add node at last position
			self.tail.next = new_node
		
		self.tail = new_node
	
	# Delete first node of queue
	def dequeue(self) :
		if (self.front != None) :
			if (self.tail == self.front) :
				self.tail = None
				self.front = None
			else :
				self.front = self.front.next
			
		
	
	def is_empty(self) :
		if (self.front == None) :
			return True
		else :
			return False
		
	

class BinaryTree :
	
	def __init__(self) :
		#  Set initial tree root to null
		self.root = None
	
	def is_k_level_sum(self, queue, level, k) :
		if (queue.is_empty() == True) :
			return False
		
		sum = 0
		temp = queue.front
		# Count number of nodes in given level
		while (temp != None and temp.level == level) :
			sum += temp.element.data
			temp = temp.next
		
		if (sum == k) :
			return True
		else :
			return False
		
	
	# Print all levels which sum is equal to given value
	def level_sum(self, k) :
		if (self.root == None) :
			print("\n Empty Binary Tree \n", end = "")
		else :
			# Get top node in tree
			node = self.root
			# Create a Queue
			queue = MyQueue()
			# Add first node at the level of one
			queue.enqueue(node, 1)
			temp = queue.front
			level = 0
			# Add tree level
			while (temp != None) :
				node = temp.element
				level = temp.level
				if (node.left != None) :
					# Add left node
					queue.enqueue(node.left, level + 1)
				
				if (node.right != None) :
					# Add right node
					queue.enqueue(node.right, level + 1)
				
				temp = temp.next
			
			status = False
			level = 0
			while (queue.is_empty() == False) :
				level = queue.front.level
				status = self.is_k_level_sum(queue, level, k)
				if (status == True) :
					print(" [", end = "")
				
				#  When level nodes sum is equal to k, 
				#  Then this loop are printed node value and remove level nodes
				#  Otherwise it's removing current level nodes
				while (queue.is_empty() == False and queue.front.level == level) :
					if (status == True) :
						# When sum exist
						print(" ", queue.front.element.data, end = "")
					
					# remove  a queue node
					queue.dequeue()
				
				if (status == True) :
					print(" ]\n", end = "")
				
			
		
	

def main() :
	# Object of Binary Tree
	tree = BinaryTree()
	#   
	# 		Construct Binary Tree
	# 		-----------------------
	# 		           10
	# 		         /   \
	# 		        2     3
	# 		       /     / \
	# 		      4     1   5
	# 		     /  \    \    \
	# 		    7    3    6   11
	# 		        /  \     /
	# 		       5    8   -3
	# 		           / \    
	# 		         -1   11
	# 		-----------------------
	# 		
	
	# Add node
	tree.root = TreeNode(10)
	tree.root.left = TreeNode(2)
	tree.root.right = TreeNode(3)
	tree.root.right.right = TreeNode(5)
	tree.root.right.left = TreeNode(1)
	tree.root.left.left = TreeNode(4)
	tree.root.left.left.left = TreeNode(7)
	tree.root.left.left.right = TreeNode(3)
	tree.root.right.left.right = TreeNode(6)
	tree.root.right.right.right = TreeNode(11)
	tree.root.right.right.right.left = TreeNode(-3)
	tree.root.left.left.right.left = TreeNode(5)
	tree.root.left.left.right.right = TreeNode(8)
	tree.root.left.left.right.right.left = TreeNode(-1)
	tree.root.left.left.right.right.right = TreeNode(11)
	tree.level_sum(10)

if __name__ == "__main__": main()

Output

 [  10 ]
 [  4  1  5 ]
 [  5  8  -3 ]
 [  -1  11 ]
#   Ruby program 
#   Print all K-sum levels in a Binary Tree

# Binary Tree node
class TreeNode  
	# Define the accessor and reader of class TreeNode  
	attr_reader :data, :left, :right
	attr_accessor :data, :left, :right
 
	
	def initialize(data) 
		# set node value
		self.data = data
		self.left = nil
		self.right = nil
	end

end

#  Queue Node
class QueueNode  
	# Define the accessor and reader of class QueueNode  
	attr_reader :element, :next, :level
	attr_accessor :element, :next, :level
 
	
	def initialize(element, level) 
		self.element = element
		self.next = nil
		self.level = level
	end

end

# Define custom queue class
class MyQueue  
	# Define the accessor and reader of class MyQueue  
	attr_reader :front, :tail
	attr_accessor :front, :tail
 
	
	def initialize() 
		self.front = nil
		self.tail = nil
	end

	# Add a new node at last of queue
	def enqueue(element, level) 
		new_node = QueueNode.new(element, level)
		if (self.front == nil) 
			# When first node of queue
			self.front = new_node
		else 
			# Add node at last position
			self.tail.next = new_node
		end

		self.tail = new_node
	end

	# Delete first node of queue
	def dequeue() 
		if (self.front != nil) 
			if (self.tail == self.front) 
				self.tail = nil
				self.front = nil
			else 
				self.front = self.front.next
			end

		end

	end

	def is_empty() 
		if (self.front == nil) 
			return true
		else 
			return false
		end

	end

end

class BinaryTree  
	# Define the accessor and reader of class BinaryTree  
	attr_reader :root
	attr_accessor :root
 
	
	def initialize() 
		#  Set initial tree root to null
		self.root = nil
	end

	def is_k_level_sum(queue, level, k) 
		if (queue.is_empty() == true) 
			return false
		end

		sum = 0
		temp = queue.front
		# Count number of nodes in given level
		while (temp != nil && temp.level == level) 
			sum += temp.element.data
			temp = temp.next
		end

		if (sum == k) 
			return true
		else 
			return false
		end

	end

	# Print all levels which sum is equal to given value
	def level_sum(k) 
		if (self.root == nil) 
			print("\n Empty Binary Tree \n")
		else 
			# Get top node in tree
			node = self.root
			# Create a Queue
			queue = MyQueue.new()
			# Add first node at the level of one
			queue.enqueue(node, 1)
			temp = queue.front
			level = 0
			# Add tree level
			while (temp != nil) 
				node = temp.element
				level = temp.level
				if (node.left != nil) 
					# Add left node
					queue.enqueue(node.left, level + 1)
				end

				if (node.right != nil) 
					# Add right node
					queue.enqueue(node.right, level + 1)
				end

				temp = temp.next
			end

			status = false
			level = 0
			while (queue.is_empty() == false) 
				level = queue.front.level
				status = self.is_k_level_sum(queue, level, k)
				if (status == true) 
					print(" [")
				end

				#  When level nodes sum is equal to k, 
				#  Then this loop are printed node value and remove level nodes
				#  Otherwise it's removing current level nodes
				while (queue.is_empty() == false && queue.front.level == level) 
					if (status == true) 
						# When sum exist
						print(" ", queue.front.element.data)
					end

					# remove  a queue node
					queue.dequeue()
				end

				if (status == true) 
					print(" ]\n")
				end

			end

		end

	end

end

def main() 
	# Object of Binary Tree
	tree = BinaryTree.new()
	#   
	# 		Construct Binary Tree
	# 		-----------------------
	# 		           10
	# 		         /   \
	# 		        2     3
	# 		       /     / \
	# 		      4     1   5
	# 		     /  \    \    \
	# 		    7    3    6   11
	# 		        /  \     /
	# 		       5    8   -3
	# 		           / \    
	# 		         -1   11
	# 		-----------------------
	# 		
	
	# Add node
	tree.root = TreeNode.new(10)
	tree.root.left = TreeNode.new(2)
	tree.root.right = TreeNode.new(3)
	tree.root.right.right = TreeNode.new(5)
	tree.root.right.left = TreeNode.new(1)
	tree.root.left.left = TreeNode.new(4)
	tree.root.left.left.left = TreeNode.new(7)
	tree.root.left.left.right = TreeNode.new(3)
	tree.root.right.left.right = TreeNode.new(6)
	tree.root.right.right.right = TreeNode.new(11)
	tree.root.right.right.right.left = TreeNode.new(-3)
	tree.root.left.left.right.left = TreeNode.new(5)
	tree.root.left.left.right.right = TreeNode.new(8)
	tree.root.left.left.right.right.left = TreeNode.new(-1)
	tree.root.left.left.right.right.right = TreeNode.new(11)
	tree.level_sum(10)
end

main()

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
/* 
  Scala program 
  Print all K-sum levels in a Binary Tree
*/

//Binary Tree node
class TreeNode(var data: Int,
	var left: TreeNode,
		var right: TreeNode)
{
	def this(data: Int)
	{
		this(data, null, null);
	}
}
// Queue Node
class QueueNode(var element: TreeNode,
	var next: QueueNode,
		var level: Int)
{
	def this(element: TreeNode, level: Int)
	{
		this(element, null, level);
	}
}
//Define custom queue class
class MyQueue(var front: QueueNode,
	var tail: QueueNode)
{
	def this()
	{
		this(null, null);
	}
	//Add a new node at last of queue
	def enqueue(element: TreeNode, level: Int): Unit = {
		var new_node: QueueNode = new QueueNode(element, level);
		if (this.front == null)
		{
			//When first node of queue
			this.front = new_node;
		}
		else
		{
			//Add node at last position
			this.tail.next = new_node;
		}
		this.tail = new_node;
	}
	//Delete first node of queue
	def dequeue(): Unit = {
		if (this.front != null)
		{
			if (this.tail == this.front)
			{
				this.tail = null;
				this.front = null;
			}
			else
			{
				this.front = this.front.next;
			}
		}
	}
	def is_empty(): Boolean = {
		if (this.front == null)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}
class BinaryTree(var root: TreeNode)
{
	def this()
	{
		this(null);
	}
	def is_k_level_sum(queue: MyQueue, level: Int, k: Int): Boolean = {
		if (queue.is_empty() == true)
		{
			return false;
		}
		var sum: Int = 0;
		var temp: QueueNode = queue.front;
		//Count number of nodes in given level
		while (temp != null && temp.level == level)
		{
			sum += temp.element.data;
			temp = temp.next;
		}
		if (sum == k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	def level_sum(k: Int): Unit = {
		if (this.root == null)
		{
			print("\n Empty Binary Tree \n");
		}
		else
		{
			//Get top node in tree
			var node: TreeNode = this.root;
			//Create a Queue
			var queue: MyQueue = new MyQueue();
			//Add first node at the level of one
			queue.enqueue(node, 1);
			var temp: QueueNode = queue.front;
			var level: Int = 0;
			//Add tree level
			while (temp != null)
			{
				node = temp.element;
				level = temp.level;
				if (node.left != null)
				{
					//Add left node
					queue.enqueue(node.left, level + 1);
				}
				if (node.right != null)
				{
					//Add right node
					queue.enqueue(node.right, level + 1);
				}
				temp = temp.next;
			}
			var status: Boolean = false;
			level = 0;
			while (queue.is_empty() == false)
			{
				level = queue.front.level;
				status = is_k_level_sum(queue, level, k);
				if (status == true)
				{
					print(" [");
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it's removing current level nodes
				while (queue.is_empty() == false && queue.front.level == level)
				{
					if (status == true)
					{
						//When sum exist
						print(" " + queue.front.element.data);
					}
					//remove  a queue node
					queue.dequeue();
				}
				if (status == true)
				{
					print(" ]\n");
				}
			}
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		//Object of Binary Tree
		var tree: BinaryTree = new BinaryTree();
		/*  
				Construct Binary Tree
				-----------------------
				           10
				         /   \
				        2     3
				       /     / \
				      4     1   5
				     /  \    \    \
				    7    3    6   11
				        /  \     /
				       5    8   -3
				           / \    
				         -1   11

				-----------------------
				*/
		//Add node
		tree.root = new TreeNode(10);
		tree.root.left = new TreeNode(2);
		tree.root.right = new TreeNode(3);
		tree.root.right.right = new TreeNode(5);
		tree.root.right.left = new TreeNode(1);
		tree.root.left.left = new TreeNode(4);
		tree.root.left.left.left = new TreeNode(7);
		tree.root.left.left.right = new TreeNode(3);
		tree.root.right.left.right = new TreeNode(6);
		tree.root.right.right.right = new TreeNode(11);
		tree.root.right.right.right.left = new TreeNode(-3);
		tree.root.left.left.right.left = new TreeNode(5);
		tree.root.left.left.right.right = new TreeNode(8);
		tree.root.left.left.right.right.left = new TreeNode(-1);
		tree.root.left.left.right.right.right = new TreeNode(11);
		tree.level_sum(10);
	}
}

Output

 [ 10 ]
 [ 4 1 5 ]
 [ 5 8 -3 ]
 [ -1 11 ]
/* 
  Swift 4 program 
  Print all K-sum levels in a Binary Tree
*/

//Binary Tree node
class TreeNode
{
	var data: Int;
	var left: TreeNode? ;
	var right: TreeNode? ;
	init(_ data: Int)
	{
		//set node value
		self.data = data;
		self.left = nil;
		self.right = nil;
	}
}
// Queue Node
class QueueNode
{
	var element: TreeNode? ;
	var next: QueueNode? ;
	var level: Int;
	init(_ element: TreeNode? , _ level : Int)
	{
		self.element = element;
		self.next = nil;
		self.level = level;
	}
}
//Define custom queue class
class MyQueue
{
	var front: QueueNode? ;
	var tail: QueueNode? ;
	init()
	{
		self.front = nil;
		self.tail = nil;
	}
	//Add a new node at last of queue
	func enqueue(_ element: TreeNode? , _ level : Int)
	{
		let new_node: QueueNode? = QueueNode(element, level);
		if (self.front == nil)
		{
			//When first node of queue
			self.front = new_node;
		}
		else
		{
			//Add node at last position
			self.tail!.next = new_node;
		}
		self.tail = new_node;
	}
	//Delete first node of queue
	func dequeue()
	{
		if (self.front != nil)
		{
			if (self.tail === self.front)
			{
				self.tail = nil;
				self.front = nil;
			}
			else
			{
				self.front = self.front!.next;
			}
		}
	}
	func is_empty() -> Bool
	{
		if (self.front == nil)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}
class BinaryTree
{
	var root: TreeNode? ;
	init()
	{
		// Set initial tree root to null
		self.root = nil;
	}
	func is_k_level_sum(_ queue: MyQueue, _ level: Int, _ k: Int) -> Bool
	{
		if (queue.is_empty() == true)
		{
			return false;
		}
		var sum: Int = 0;
		var temp: QueueNode? = queue.front;
		//Count number of nodes in given level
		while (temp != nil && temp!.level == level)
		{
			sum += temp!.element!.data;
			temp = temp!.next;
		}
		if (sum == k)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//Print all levels which sum is equal to given value
	func level_sum(_ k: Int)
	{
		if (self.root == nil)
		{
			print("\n Empty Binary Tree \n", terminator: "");
		}
		else
		{
			//Get top node in tree
			var node: TreeNode? = self.root;
			//Create a Queue
			let queue: MyQueue = MyQueue();
			//Add first node at the level of one
			queue.enqueue(node, 1);
			var temp: QueueNode? = queue.front;
			var level: Int = 0;
			//Add tree level
			while (temp != nil)
			{
				node = temp!.element;
				level = temp!.level;
				if (node!.left != nil)
				{
					//Add left node
					queue.enqueue(node!.left, level + 1);
				}
				if (node!.right != nil)
				{
					//Add right node
					queue.enqueue(node!.right, level + 1);
				}
				temp = temp!.next;
			}
			var status: Bool = false;
			level = 0;
			while (queue.is_empty() == false)
			{
				level = queue.front!.level;
				status = self.is_k_level_sum(queue, level, k);
				if (status == true)
				{
					print(" [", terminator: "");
				}
				// When level nodes sum is equal to k, 
				// Then this loop are printed node value and remove level nodes
				// Otherwise it"s removing current level nodes
				while (queue.is_empty() == false && queue.front!.level == level)
				{
					if (status == true)
					{
						//When sum exist
						print(" ", queue.front!.element!.data, terminator: "");
					}
					//remove  a queue node
					queue.dequeue();
				}
				if (status == true)
				{
					print(" ]\n", terminator: "");
				}
			}
		}
	}
}
func main()
{
	//Object of Binary Tree
	let tree: BinaryTree = BinaryTree();
	tree.root = TreeNode(10);
	tree.root!.left = TreeNode(2);
	tree.root!.right = TreeNode(3);
	tree.root!.right!.right = TreeNode(5);
	tree.root!.right!.left = TreeNode(1);
	tree.root!.left!.left = TreeNode(4);
	tree.root!.left!.left!.left = TreeNode(7);
	tree.root!.left!.left!.right = TreeNode(3);
	tree.root!.right!.left!.right = TreeNode(6);
	tree.root!.right!.right!.right = TreeNode(11);
	tree.root!.right!.right!.right!.left = TreeNode(-3);
	tree.root!.left!.left!.right!.left = TreeNode(5);
	tree.root!.left!.left!.right!.right = TreeNode(8);
	tree.root!.left!.left!.right!.right!.left = TreeNode(-1);
	tree.root!.left!.left!.right!.right!.right = TreeNode(11);
	tree.level_sum(10);
}
main();

Output

 [  10 ]
 [  4  1  5 ]
 [  5  8  -3 ]
 [  -1  11 ]

Output Explanation

The code implements the algorithm and prints the levels of the binary tree where the sum of nodes' values is equal to the given K. It displays the nodes' values for each level in square brackets.

Time Complexity

The time complexity of this algorithm is O(N), where N is the number of nodes in the binary tree. This is because we perform a BFS traversal through all nodes of the binary tree. The space complexity is also O(N), as we use a queue for BFS traversal.





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