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Binary Tree Level Order Traversal

Explore how to implement binary tree level order traversal by using breadth-first search techniques. Learn to return all node values in a string format separated by colons, handling empty trees correctly. This lesson helps you understand traversal logic and coding implementation of tree BFS in C++.

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Statement

Given the root of a binary tree, display the values of its nodes while performing a level order traversal. Return the node values for all levels in a string separated by the character :. If the tree is empty, i.e., the number of nodes is 00, then return “None” as the output.

Constraints:

  • The number of nodes in the tree is in the range [0,500][0, 500].

  • −103≤-10^3 \leq Node.data ≤103\leq 10^3

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Technical Quiz
1.

How does BFS ensure that it visits all nodes in a binary tree while traversing level by level?

A.

By using a stack data structure to keep track of visited nodes

B.

By using a queue data structure to maintain the order of node exploration

C.

By recursively traversing the left and right subtrees in a depth-first manner

D.

By randomizing the order of node exploration for better coverage

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
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5

Try it yourself

Implement your solution in main.cpp in the following coding playground.

Note: The binary tree node’s class has members left and right to store references to other nodes and the member data to hold the node’s value.

C++
usercode > main.cpp
#include <iostream>

#include <iostream>

#include <vector>



// Definition for a binary tree node

// template<class T>

// class TreeNode {

// public:

//     T data;

//     TreeNode<T>* left;

//     TreeNode<T>* right;



//     TreeNode(const T data) : data(data), left(nullptr), right(nullptr) {}

// };



string LevelOrderTraversal(TreeNode<int>* root)

{



	// Replace this placeholder return statement with your code

	return "";

}
Binary Tree Level Order Traversal