BFS

from collections import deque


class Graph:
    # constructor
    def __init__(self, edges, n):
        self.adjList = [[] for _ in range(n)]

        # Add edges to undirected graph
        for (src, dest) in edges:
            self.adjList[src].append(dest)
            self.adjList[dest].append(src)


# Perform BFS recursively on the graph
def recursiveBFS(graph, q, discovered):
    if not q:
        return
    # deque front node and print it
    v = q.popleft()
    print(v, end='')

# do for every egde
    for u in graph.adjList[v]:
        if not discovered[u]:
        # mark it as discovered and enqueue ot
        discovered[u] = True
        q.append(u)

    recursiveBFS(graph, q, discovered)

if __name__ == "__main__":
    # List of graph edges for diagram
    edges = [
        (1, 2), (1, 3), (1, 4), (2, 5), (2, 6),
        (3, 10), (3, 7), (4, 8), (4, 11)
    ]

n = 12

#build a graph
graph = Graph(edges, n)