advent-of-code/2021/python/day12.py

52 lines
1.4 KiB
Python
Raw Normal View History

2022-12-09 16:43:00 +00:00
import matrix
import shared
from collections import defaultdict
START = 'start'
END = 'end'
class Passage:
def __init__(self, name):
self.load(name)
self.parse_connections()
def load(self, name):
lines= []
with open(name, 'r') as f:
for line in f.readlines():
lines.append(line.rstrip())
self.instructions = lines
def parse_connections(self):
connections = defaultdict(list)
for edge in self.instructions:
node1, node2 = edge.split('-')
# Add bidirectional
connections[node1].append(node2)
connections[node2].append(node1)
self.connections = connections
def traverse(self, multiple_entry, enter=START, seen={START}):
if enter == END: # we're done!
yield 1
return
for node in self.connections[enter]:
if node.islower():
if node not in seen:
yield from self.traverse(multiple_entry, node, seen | {node})
elif multiple_entry and node not in {START, END}:
yield from self.traverse(False, node, seen | {node})
else:
yield from self.traverse(multiple_entry, node, seen)
def main():
p = Passage(shared.get_fname(12))
print(sum(p.traverse(multiple_entry=False)))
print(sum(p.traverse(multiple_entry=True)))
if __name__ == "__main__":
main()