# What is Level Order Traversal and implementation

In this blog, we would discuss what is Level Order Traversal and its implementation. In computer science, a level-order traversal is a traversal of a tree in which the nodes are visited in order from top to bottom, and at each level from left to right. This is also known as a breadth-first traversal, as it visits all the nodes at each level before moving on to the next level. A level-order traversal can be used to find the shortest path between two nodes in a tree, as it will always find the path with the fewest number of edges.

It can also be used to find the maximum or minimum value in a tree, as it will always visit the nodes in order from left to right. To perform a level-order traversal, we can use a queue to keep track of the nodes at each level. We start by enqueuing the root node, and then we dequeue a node and enqueue all of its child nodes. We continue this process until the queue is empty. Here is an example of a level-order traversal of a binary tree:

## What is Level order traversal?

A level order traversal of a tree is a traversal in which the nodes are visited in order from left to right, starting at the root. The level order traversal of a tree is a very powerful tool for traversing and manipulating trees. It is often used in conjunction with other traversals, such as in-order and preorder traversals. This is a very simple traversal to perform and can be done using a queue.

To do a level order traversal, we first need to create a queue. We then visit the root node and add its children to the queue. We then visit the next node in the queue and add its children to the queue. A level order traversal is a very efficient way to visit all of the nodes in a tree. It is also very easy to implement since it can be done using a simple queue.

**1**

** / \**

** 2 3**

** / \ \**

** 4 5 6**

We would enqueue the nodes in the order: **1, 2, 3, 4, 5, 6.**

We would dequeue the nodes in the order: **1, 2, 3, 4, 5, 6.**

## Implementation of Level Order Traversal

class Node: def __init__(self, key): self.data = key self.left = None self.right = None def printLevelOrder(root): # Base Case if root is None: return queue = [] # Enqueue Root and initialize height queue.append(root) while(len(queue) > 0): print(queue[0].data) node = queue.pop(0) if node.left is not None: queue.append(node.left) if node.right is not None: queue.append(node.right) # Driver Program to test above function root = Node(1) root.left = Node(2) root.right = Node(3) root.left.left = Node(4) root.left.right = Node(5) print("Level Order Traversal of binary tree is -") printLevelOrder(root)

## Uses of Level Order Traversal

- The level order traversal can be used to find the shortest path between two nodes in a tree. It can also be used to find the longest path between two nodes in a tree.

- The level order traversal can also be used to find the diameter of a tree. The diameter of a tree is the length of the longest path between any two nodes in the tree.

- The level order traversal can also be used to find the height of a tree. The height of a tree is the length of the longest path from the root node to any leaf node.

- The level order traversal can also be used to find the size of a tree. The size of a tree is the number of nodes in the tree.

- The level order traversal can also be used to find the depth of a tree. The depth of a tree is the length of the longest path from the root node to any other node in the tree.

Also, read about post-order traversal and its implementation.

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