In this series, I'll share my progress with the 2023 version of Advent of Code.
Check the first post for a short intro to this series.
You can also follow my progress on GitHub.
December 8th
The puzzle of day 8 was not so hard. I like graph problems, although this was pretty basic.
My pitfall for this puzzle: I have no clue how to find the number that's a common factor for all path lengths. Something similar to Greatest Common Divisor, but what 🤷. In the end a brute force approach worked and doesn't take that long on my M1 laptop.
Solution here, do not click if you want to solve the puzzle first yourself
#!/usr/bin/env python3
import math
with open('input.txt') as infile:
lines = infile.readlines()
directions = [d for d in lines[0].strip()]
graph = {}
for line in lines[2:]:
parts = line.strip().split(' = ')
targets = parts[1][1:-1].split(', ')
graph[parts[0]] = {'L': targets[0], 'R': targets[1]}
dir_idx = 0
steps = 0
nodes = [n for n in graph.keys() if n.endswith('A')]
finished = []
while len([n for n in nodes if not n.endswith('Z')]) > 0:
steps += 1
for idx, n in enumerate(nodes):
if idx in [f[0] for f in finished]:
continue
nodes[idx] = graph[n][directions[dir_idx]]
if nodes[idx].endswith('Z'):
finished.append((idx, steps))
if dir_idx < len(directions) - 1:
dir_idx += 1
else:
dir_idx = 0
for f in finished:
print(f'Finished node {f[0]} in {f[1]} steps')
highest = max([f[1] for f in finished])
total = highest
while True:
all_divisors = True
for f in finished:
if total % f[1] != 0:
all_divisors = False
if all_divisors:
break
else:
total += highest
print(total)
That's it! See you again tomorrow!
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