Breadth-First Search in Python
In Python, the breadth-first and depth-first search techniques are implemented to search a tree or graph. These two are among the most crucial topics for every new Python coder to master. We'll look at what exactly breadth-first search is in Python, how its algorithm works, how to implement it in Python with an example code, and the results. We'll also learn about bfs' real-world applications and usage of breadth-first search.
What is Breadth-First Search?
Breadth-First Search (BFS) is a method for searching graphs or trees, as previously mentioned. Traversing the tree entails visiting every node. Breadth-First Search is a recursive method for searching all the nodes of a tree or graph. In Python, We can utilize data structures like lists or tuples to perform BFS. In trees and graphs, the breadth-first search is virtually identical. The only distinction is that the tree might have loops, which would enable us to revisit the same node.
Let's look over the methodology Breadth-First uses prior to learning to write a Python code for it and discuss its output. Consider Rubik's Cube as an analogy. The Rubik's Cube is thought to be looking for a way to turn it from a jumble of hues into a single color. When comparing the Rubik's Cube to a tree or a graph, we can conclude that the cube's potential states correlate to the vertices of our network, and the cube's potential actions correlate to the graph's edges.
The bfs algorithm follows the steps discussed below.
As breadth-first search scans every node of the given graph, a standard BFS algorithm splits each node or vertex of the tree or graph into two distinct groups.
The objective of the technique discussed is to visit each vertex while at the same time avoiding recurring cycles. BFS starts with a single node, then examines all nodes inside one distance, then all the other nodes under two distances, and so forth. To retain the nodes that remained to visit, BFS requires a queue (or, in Python, a list).
The Breadth First Search Traversal for The Graph is as Follows: 3 1
We have first generated the graph in the Python program shown above, for which we have applied the breadth-first search approach. After that, we have initialized two lists: one is to keep track of the nodes of the graph the BFS algorithm has visited, and another is to keep track of the nodes inside the queue.
We have declared a function with parameters visited nodes, the graph itself, and the node following the above steps. We have to keep adding the visited_vertices and queue lists within a function.
Then the program will execute the while loop on the queue of nodes yet to visit and then erase and display the current node as it has visited. Finally, we have used the for loop to look for unvisited nodes before appending them to the visited_vertices and queue lists. We then called the BFSearch function with the argument, which is the very first we want in the output.
The Breadth-first Search algorithm has a temporal complexity of O(V+E), wherein V represents the number of vertices and E represents the number of links. Furthermore, the BFS algorithm has O(V) space complexity.
Applications of Breadth First Traversal