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Commit 7fd03ce

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day13 outch
1 parent ed9b754 commit 7fd03ce

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3 files changed

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lines changed

3 files changed

+60
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lines changed

‎2020/day13/data.txt

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1002460
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29,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,41,x,x,x,x,x,x,x,x,x,601,x,x,x,x,x,x,x,23,x,x,x,x,13,x,x,x,17,x,19,x,x,x,x,x,x,x,x,x,x,x,463,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,37

‎2020/day13/data_test.txt

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939
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7,13,x,x,59,x,31,19

‎2020/day13/main.rb

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#!/usr/bin/ruby
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require 'matrix'
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require 'test/unit'
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require 'pry'
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def extract_data(name)
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data = File.read(name).split("\n")
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[data[0].to_i, data[1].split(',').map(&:to_i)]
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end
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def resolve_1(data)
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data[1].reject { |e| e == 0 }.inject({ id: nil, time: Float::INFINITY }) { |h, id|
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time = - (data[0] % id) + id
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time < h[:time] ? { id: id, time: time, result: id * time } : h
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}[:result]
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end
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def resolve_2(data)
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result = { first: 0, period: 1 }
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data[1].each_with_index do |v, delta|
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result = find_pair_match(result, v, delta)
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end
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result[:first]
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end
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def find_pair_match(result, b, offset)
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return result if b == 0 # 'x'
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a = result[:period]
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time = result[:first]
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while (time + offset) % b != 0
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time += result[:period]
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end
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{ first: time, period: a * b }
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end
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class Day12Test < Test::Unit::TestCase
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def test_star_1
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data = extract_data('data_test.txt')
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assert_equal 295, resolve_1(data)
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end
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def test_star_1_final
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data = extract_data('data.txt')
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assert_equal 4808, resolve_1(data)
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end
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def test_star_2
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data = extract_data('data_test.txt')
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assert_equal 1068781, resolve_2(data)
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end
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def test_star_2_final
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data = extract_data('data.txt')
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assert_equal 741745043105674, resolve_2(data)
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end
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end

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