def shortestAlternatingPaths(self, n: int, red_edges: List[List[int]],
blue_edges: List[List[int]]) -> List[int]:
dist = [float('inf')] * n
dist[0] = 0
re = {i: [] for i in range(n)}
be = {i: [] for i in range(n)}
for u, v in red_edges:
re[u].append(v)
for u, v in blue_edges:
be[u].append(v)
queue = Deque([(0, 0, 'b'), (0, 0, 'r')])
vis = {(0, 'b'): True, (0, 'r'): True}
while queue:
node, level, color = queue.popleft()
if color == 'b' or color == None:
for neig in re[node]:
if (neig, "r") not in vis:
dist[neig] = min(dist[neig], level + 1)
queue.append((neig, level + 1, 'r'))
vis[(neig, 'r')] = True
if color == 'r' or color == None:
for neig in be[node]:
if (neig, "b") not in vis:
dist[neig] = min(dist[neig], level + 1)
queue.append((neig, level + 1, 'b'))
vis[(neig, 'b')] = True
return [-1 if val == float('inf') else val for val in dist]
def test_length(self):
q = Deque()
assert q.length() == 0
q.push_front('A')
assert q.length() == 1
q.push_front('B')
assert q.length() == 2
q.pop_front()
assert q.length() == 1
q.pop_front()
assert q.length() == 0
def test_is_empty(self):
q = Deque()
assert q.is_empty() is True
q.push_front('A')
assert q.is_empty() is False
q.pop_front()
assert q.is_empty() is True
q.push_back('A')
assert q.is_empty() is False
q.pop_back()
assert q.is_empty() is True
def test_pop_back(self):
q = Deque(['A', 'B', 'C'])
assert q.pop_back() == 'C'
assert q.length() == 2
assert q.pop_back() == 'B'
assert q.length() == 1
assert q.pop_back() == 'A'
assert q.length() == 0
assert q.is_empty() is True
with self.assertRaises(ValueError):
q.pop_back()
def test_back(self):
q = Deque()
assert q.back() is None
q.push_back('A')
assert q.back() == 'A'
q.push_back('B')
assert q.back() == 'B'
q.pop_back()
assert q.back() == 'A'
q.pop_front()
assert q.back() is None
def test_push_back(self):
q = Deque()
q.push_back('A')
assert q.front() == 'A'
assert q.back() == 'A'
assert q.length() == 1
q.push_back('B')
assert q.front() == 'A'
assert q.back() == 'B'
assert q.length() == 2
q.push_back('C')
assert q.front() == 'A'
assert q.back() == 'C'
assert q.length() == 3
assert q.is_empty() is False
def test_init_with_list(self):
q = Deque(['A', 'B', 'C'])
assert q.front() == 'A'
assert q.back() == 'C'
assert q.length() == 3
assert q.is_empty() is False
def test_init(self):
q = Deque()
assert q.front() is None
assert q.back() is None
assert q.length() == 0
assert q.is_empty() is True