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Day 8 - simpler and (much) faster

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Stefan Harmuth 2023-12-08 07:10:34 +01:00
parent fdfa8a02b2
commit b3bddd521f
1 changed files with 4 additions and 4 deletions
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8
day08.py
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@ -46,20 +46,20 @@ class Day(AOCDay):
inst, nodes = self.parse_input() inst, nodes = self.parse_input()
i_len = len(inst) i_len = len(inst)
check_nodes = [x for x in nodes if x.endswith("A")] check_nodes = [x for x in nodes if x.endswith("A")]
nodes_dp = defaultdict(dict) z_steps = []
for node in check_nodes: for node in check_nodes:
cur_step = 0 cur_step = 0
cur_node = node cur_node = node
while (cur_node, cur_step % i_len) not in nodes_dp[node]: while not cur_node.endswith("Z"):
nodes_dp[node][(cur_node, cur_step % i_len)] = cur_step
if inst[cur_step % i_len] == "L": if inst[cur_step % i_len] == "L":
cur_node = nodes[cur_node][0] cur_node = nodes[cur_node][0]
else: else:
cur_node = nodes[cur_node][1] cur_node = nodes[cur_node][1]
cur_step += 1 cur_step += 1
z_steps.append(cur_step)
return math.lcm(*[v for node in check_nodes for k, v in nodes_dp[node].items() if k[0].endswith("Z")]) return math.lcm(*z_steps)
if __name__ == "__main__": if __name__ == "__main__":