#!/usr/bin/env python3 # Copyright 2023 Síle Ekaterin Liszka # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the "Software"), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in # all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS # IN THE SOFTWARE. from itertools import cycle from math import lcm insns = '' data = [] with open('input.txt', mode='r') as f: data = f.readlines() insns = data[0][:-1] data = data[2:] nodes = {} for line in data: name, dest = line.split(' = ', maxsplit=1) left, right = dest[1:-2].split(', ', maxsplit=1) nodes[name] = (left, right) move = {'L': 0, 'R': 1} locs = [x for x in nodes.keys() if x.endswith('A')] steps = {} for loc in locs: orig = loc count = 0 insn = cycle(insns) while not loc.endswith('Z'): dir = next(insn) loc = nodes[loc][move[dir]] count += 1 steps[orig] = count steppy = steps.values() print(lcm(*steppy))