Find maximum level sum in Binary Tree

Hello Everyone,

Given a Binary Tree having positive and negative nodes, the task is to find the maximum sum level in it.

The idea is to do a level order traversal of the tree. While doing traversal, process nodes of different levels separately. For every level being processed, compute the sum of nodes in the level and keep track of the maximum sum.

Below is the implementation of the above idea:

// A queue based C++ program to find maximum sum

// of a level in Binary Tree

#include <bits/stdc++.h>

using namespace std;

/* A binary tree node has data, pointer to left child

and a pointer to right child */

struct Node


int data;

struct Node *left, *right;


// Function to find the maximum sum of a level in tree

// using level order traversal

int maxLevelSum( struct Node* root)


// Base case

if (root == NULL)

return 0;

// Initialize result

int result = root->data;

// Do Level order traversal keeping track of number

// of nodes at every level.

queue<Node*> q;


while (!q.empty())


// Get the size of queue when the level order

// traversal for one level finishes

int count = q.size();

// Iterate for all the nodes in the queue currently

int sum = 0;

while (count--)


// Dequeue an node from queue

Node* temp = q.front();


// Add this node's value to current sum.

sum = sum + temp->data;

// Enqueue left and right children of

// dequeued node

if (temp->left != NULL)


if (temp->right != NULL)



// Update the maximum node count value

result = max(sum, result);


return result;


/* Helper function that allocates a new node with the

given data and NULL left and right pointers. */

struct Node* newNode( int data)


struct Node* node = new Node;

node->data = data;

node->left = node->right = NULL;

return (node);


// Driver code

int main()


struct Node* root = newNode(1);

root->left = newNode(2);

root->right = newNode(3);

root->left->left = newNode(4);

root->left->right = newNode(5);

root->right->right = newNode(8);

root->right->right->left = newNode(6);

root->right->right->right = newNode(7);

cout << "Maximum level sum is " << maxLevelSum(root)

<< endl;

return 0;



Maximum level sum is 17