bfs python

'''
def createm(n):
    a = []
    for i in range(0, n):
        a.append([])
        a[i] = list(map(int, input().split()))
    return a

def bfs(v):
    global n
    global a
    global p
    q = [] #очередь
    used = [False] * n
    q += [v]
    used[v] = 1
    while len(q) != 0:
        v = q[0]
        q.pop(0)
        for to in a[v]:
            if (not used[to]):
                q += [to]
                p[to] = v
                used[to] = 1

n = int(input())
matr = createm(n)
a = []
for i in range(0, n):
    a.append([])
for i in range(0, n):
    for j in range(0, n):
        if matr[i][j] != 0:
            a[i].append(j)
s, f = map(int, input().split())
print(a)
s -= 1
f -= 1
p = [-1] * n
bfs(s)
b = []
b += [f]
while p[f] != -1:
    f = p[f]
    b += [f]
b.reverse()
if b[0] != s:
    print(-1)
else:
    if len(b) == 1:
        print(0)
        exit(0)
    print(len(b) - 1)
    for k in b:
        print(k, end = ' ')
'''