Breadth First Search (BFS) Algorithm

hi guys, on this beautiful day we'll talk about Breadth-First Search

Definition of Breadth-First Search Algorithm (BFS)

Breadth-First Search: is an algorithm that traverses and searches in trees and graphs using recursion and queue data structure, this algorithm comes to avoid processing a node more than once.

Time complexity and Space complexity of BFS

Space complexlity	O(V)
Time complexity	O(V+E)

Breadth-First Search applications

Google maps

Cheney's algorithm

Search Engines

Peer to Peer Networking

Ford-Fulkerson algorithm

Breadth-First Search approach

Initialize a queue

Mark the node as visited by inserting it to a list

Insert the vertices into the queue

While len(queue) > 0:

Delete the first item of the queue
mark as visited and push all adjacents unvisited nodes of the deleted Item.

Breadth-First Search implementation in python

If you are not familiar with python, I recommend you check this series

# CODE FROM https://favtutor.com/blogs/breadth-first-search-python

graph = {
  '5' : ['3','7'],
  '3' : ['2', '4'],
  '7' : ['8'],
  '2' : [],
  '4' : ['8'],
  '8' : []
}

visitedNodes = [] 
queue = []   

def bfs(visitedList: list, graph: dict, node):
    visitedList.append(node)
    queue.append(node)

    while queue:        
        m = queue.pop(0) 
        print (m, end = "\t") 
        for adjacent in graph[m]:
            if adjacent not in visitedList:
                visitedList.append(adjacent)
                queue.append(adjacent)

bfs(visitedNodes, graph, '5') # 5 3 7 2 4 8