In this course, we’ll use `Graph` implementation as class:

class Graph:
  def __init__(self, vertices):
    # init graph with its vertices
    self.graph = {v : [] for v in vertices}
   
  def addEdge(self, u, v):
    self.graph[u].append(v)
   
  def __str__(self):
    out = ""
    for vertex in self.graph:
      out += vertex + ":"+self.graph[vertex]
    return out


> This works for **oriented** graph. Main methods are implemented, and you’ll add some methods according to the next tasks.

This mini-course introduces the BFS Algorithm. It requires understanding the graph theory on base level, and Python programming language knowledge. This course is built on implementing step-by-step solutions and using `Graph` class implementation, so you have to understand Python OOP minimally. You have to be able to implement an algorithm by pseudocode.

Meet the BFS example and code, that you'll improve during the course.

Let's upgrade your code to make it faster and consistent.

Apply your knowledge to solve some algorithmic problems.

Graph Class Implementation