binary tree level traversal

To perform a level order traversal on a binary tree in C++, you can use a queue data structure. Here are the steps involved:

1. Create an empty queue and push the root node onto it.
2. Start a loop until the queue becomes empty.
3. Inside the loop, pop the front element from the queue and print its value.
4. If the popped element has a left child, push it onto the queue.
5. If the popped element has a right child, push it onto the queue.
6. Repeat steps 3 to 5 until the queue becomes empty.

This algorithm ensures that the elements are traversed level by level, from left to right, starting from the root node. By using a queue, we can keep track of the elements at each level and process them in the desired order.

Here is an example implementation in C++:

#include <iostream>
#include <queue>

struct Node {
    int value;
    Node* left;
    Node* right;

    Node(int val) {
        value = val;
        left = nullptr;
        right = nullptr;
    }
};

void levelOrderTraversal(Node* root) {
    if (root == nullptr)
        return;

    std::queue<Node*> q;
    q.push(root);

    while (!q.empty()) {
        Node* curr = q.front();
        q.pop();

        std::cout << curr->value << " ";

        if (curr->left != nullptr)
            q.push(curr->left);

        if (curr->right != nullptr)
            q.push(curr->right);
    }
}

int main() {
    // Create a binary tree
    Node* root = new Node(1);
    root->left = new Node(2);
    root->right = new Node(3);
    root->left->left = new Node(4);
    root->left->right = new Node(5);

    // Perform level order traversal
    levelOrderTraversal(root);

    return 0;
}

This program creates a binary tree with values 1, 2, 3, 4, and 5. It then performs a level order traversal on the tree, printing the values in the order they are visited. The output will be: 1 2 3 4 5.