hhl.py

from collections import deque

class BFSResult:
    def __init__(self):
        self.level = {}
        self.parent = {}

class Graph:
    def __init__(self):
        self.adj = {}

    def add_edge(self, u, v):
        if self.adj[u] is None:
            self.adj[u] = []
        self.adj[u].append(v)




def bfs(g, s):
    r = BFSResult()
    r.parent = {s: None}
    r.level = {s: 0}

    queue = deque()
    queue.append(s)

    while queue:
        u = queue.popleft()
        for n in g.adj[u]:
            if n not in level:
                r.parent[n] = u
                r.level[n] = r.level[u] + 1
                queue.append(n)
    return r


g = Graph()
g.add_edge(3, 5)
g.add_edge(5, 3)