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December 11, 2023 16:55
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Advent of Code 2023 day008.rb
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require_relative "main" | |
module Day008 | |
INPUT = File.read('INPUT.txt') | |
lines = INPUT.to_lines | |
instructions = lines.shift.chars | |
lines.shift | |
graph = lines.map do |line| | |
parent, children_string = line.split_strip("=") | |
children = children_string.split_strip(",").map(&:to_an) | |
[parent, children] | |
end.to_h | |
SIDE = %w[L R] | |
########## | |
# Part 1 # | |
########## | |
cursor1 = "AAA" | |
i = 0 | |
loop do | |
side = SIDE.index(instructions[i % instructions.length]) | |
cursor1 = graph[cursor1][side] | |
break if cursor1 == "ZZZ" | |
i += 1 | |
end | |
answer1 = i + 1 | |
pp answer1 | |
########## | |
# Part 2 # | |
########## | |
cursors = graph.keys.filter do |parent| | |
parent[-1] == "A" | |
end | |
sums = cursors.map do |cursor2| | |
i = 0 | |
loop do | |
side = SIDE.index(instructions[i % instructions.length]) | |
cursor2 = graph[cursor2][side] | |
break if cursor2[-1] == "Z" | |
i += 1 | |
end | |
i + 1 | |
end | |
answer2 = sums.lcm | |
pp answer2 | |
end |
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