# What Data Structure Is Used for Breadth First Traversal of a Graph?

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Heather Bennett

Data structures play a crucial role in computer science and are essential for efficient data manipulation. When it comes to graph traversal algorithms, one commonly used data structure for breadth-first traversal is the queue. In this article, we will explore why the queue data structure is suitable for performing breadth-first traversal on a graph.

Breadth-first traversal is an algorithm used in graph theory to visit all the vertices of a graph systematically. Unlike depth-first traversal, which explores as far as possible along each branch before backtracking, breadth-first traversal explores all the vertices at the same level before moving on to the next level.

### The Role of a Queue

To perform breadth-first traversal on a graph, we need a data structure that follows the FIFO (First-In-First-Out) principle. This means that the first element inserted into the data structure will be the first one to be removed. A queue is an ideal choice for this purpose.

A queue is a linear data structure that supports two basic operations: enqueue and dequeue. The enqueue operation adds an element to the end of the queue, while dequeue removes an element from the front of the queue. These operations ensure that elements are processed in the order they were added, which aligns with our goal of exploring vertices at each level before moving deeper into the graph.

### The Breadth-First Traversal Algorithm Using a Queue

Let’s now discuss how we can use a queue to implement breadth-first traversal on a graph:

1. Create an empty queue.
2. Enqueue the starting vertex into the queue.
3. Create an array or a data structure to keep track of visited vertices.
4. While the queue is not empty:
• Dequeue a vertex from the front of the queue.
• Mark the dequeued vertex as visited and process it.
• Enqueue all adjacent vertices of the dequeued vertex that haven’t been visited yet.
5. Repeat steps 4-6 until the queue becomes empty.

This algorithm ensures that each vertex is visited only once, and all its adjacent vertices are explored before moving on to the next level. By using a queue, we can maintain this order and achieve breadth-first traversal efficiently.

## Conclusion

In conclusion, when performing breadth-first traversal on a graph, the queue data structure is an excellent choice. Its FIFO nature allows us to explore all vertices at each level before moving deeper into the graph. By using a queue, we can implement an efficient algorithm that visits each vertex exactly once and guarantees breadth-first exploration.

By understanding how different data structures fit into various algorithms, we can optimize our code for better performance. So remember, when it comes to breadth-first traversal on a graph, don’t forget to bring your trusty queue along!