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69 lines
2.1 KiB
69 lines
2.1 KiB
8 years ago
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include Math
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def follow_instructions(input)
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seq = input.split(', ')
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# start facing north at the origin
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dir = -PI/2
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locations = [[0,0]]
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seq.each.with_object(locations) do |step, locations|
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/(?<turn>\w)(?<blocks>\d+)/ =~ step
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case turn
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when ?R
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dir += PI/2
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when ?L
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dir -= PI/2
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else
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raise "unexpected turn: #{turn}"
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end
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blocks.to_i.times do
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location = locations.last
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x = location[0] + cos(dir).to_i
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y = location[1] + sin(dir).to_i
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locations << [x, y]
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end
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end
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locations
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end
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def first_dupe(ary)
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seen = Set.new
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ary.find { |elem|
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seen.include?(elem) || (seen << elem && false)
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}
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end
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require 'minitest'
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# require 'minitest/autorun'
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class TestInstructions < Minitest::Test
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def test_instructions
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assert_distance 5, 'R2, L3'
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assert_distance 2, 'R2, R2, R2'
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assert_distance 12, 'R5, L5, R5, R3'
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end
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def test_first_dupe
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assert_equal 1, first_dupe([1, 2, 3, 1])
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assert_equal 2, first_dupe([1, 2, 3, 2])
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assert_equal 3, first_dupe([1, 2, 3, 3])
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locations = follow_instructions('R8, R4, R4, R8')
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assert_equal [4, 0], first_dupe(locations)
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end
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def assert_distance(expected, instructions)
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locations = follow_instructions(instructions)
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assert_equal expected, locations.last.map(&:abs).inject(:+)
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end
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end
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if __FILE__ == $0
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puts first_dupe(follow_instructions(DATA.read))
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end
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__END__
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R4, R3, L3, L2, L1, R1, L1, R2, R3, L5, L5, R4, L4, R2, R4, L3, R3, L3, R3, R4, R2, L1, R2, L3, L2, L1, R3, R5, L1, L4, R2, L4, R3, R1, R2, L5, R2, L189, R5, L5, R52, R3, L1, R4, R5, R1, R4, L1, L3, R2, L2, L3, R4, R3, L2, L5, R4, R5, L2, R2, L1, L3, R3, L4, R4, R5, L1, L1, R3, L5, L2, R76, R2, R2, L1, L3, R189, L3, L4, L1, L3, R5, R4, L1, R1, L1, L1, R2, L4, R2, L5, L5, L5, R2, L4, L5, R4, R4, R5, L5, R3, L1, L3, L1, L1, L3, L4, R5, L3, R5, R3, R3, L5, L5, R3, R4, L3, R3, R1, R3, R2, R2, L1, R1, L3, L3, L3, L1, R2, L1, R4, R4, L1, L1, R3, R3, R4, R1, L5, L2, R2, R3, R2, L3, R4, L5, R1, R4, R5, R4, L4, R1, L3, R1, R3, L2, L3, R1, L2, R3, L3, L1, L3, R4, L4, L5, R3, R5, R4, R1, L2, R3, R5, L5, L4, L1, L1
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