def sync(self, pk, payload):
"""Update hg and return new event ids in topological order."""
info = crypto_sign(dumps({c: self.height[h]
for c, h in self.can_see[self.head].items()}), self.sk)
msg = crypto_sign_open(self.network[pk](self.pk, info), pk)
remote_head, remote_hg = loads(msg)
new = tuple(toposort(remote_hg.keys() - self.hg.keys(),
lambda u: remote_hg[u].p))
for h in new:
ev = remote_hg[h]
if self.is_valid_event(h, ev):
self.add_event(h, ev)
if self.is_valid_event(remote_head, remote_hg[remote_head]):
h, ev = self.new_event(payload, (self.head, remote_head))
# this really shouldn't fail, let's check it to be sure
assert self.is_valid_event(h, ev)
self.add_event(h, ev)
self.head = h
return new + (h,)
def longest_path_in_dag(g: AdjList, w: EdgeWeight, start: Hashable,
goal: Hashable) -> Tuple[int, Path]:
"""
>>> g = {0: [1, 2], 1: [4], 2: [3], 3: [4]}
>>> w = {(0, 1): 7, (0, 2): 4, (2, 3): 2, (1, 4): 1, (3, 4): 3}
>>> longest_path_in_dag(g, w, 0, 4)
(9, [0, 2, 3, 4])
"""
g_pred = collections.defaultdict(list)
for x, preds in g.items():
for pred in preds:
g_pred[pred].append(x)
vs = toposort(g)
dp = collections.defaultdict(lambda: -1000000)
pred = dict()
dp[start] = 0
for v in vs:
if v == start:
continue
for v_prev in g_pred.get(v, []):
if dp[v] < (newmax := dp[v_prev] + w[v_prev, v]):
dp[v] = newmax
pred[v] = v_prev