# 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;`

` ` `q.push(root);`

` ` `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();`

` ` `q.pop();`

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

` ` `sum = sum + temp->data;`

` ` `// Enqueue left and right children of`

` ` `// dequeued node`

` ` `if` `(temp->left != NULL)`

` ` `q.push(temp->left);`

` ` `if` `(temp->right != NULL)`

` ` `q.push(temp->right);`

` ` `}`

` ` `// 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;`

`}`

Output

Maximum level sum is 17