57 lines
1.1 KiB
Ruby
57 lines
1.1 KiB
Ruby
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class DirectionString
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attr_reader :string, :start_position
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def initialize(string, start_position=[1, 1])
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@string = string
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@start_position = start_position
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end
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def final_position
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return start_position if string.empty?
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self.class.new(string[1..], next_position).final_position
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end
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def next_position
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case string[0]
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when "D"
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[start_position[0], start_position[1] + 1]
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when "U"
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[start_position[0], start_position[1] - 1]
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when "L"
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[start_position[0] - 1, start_position[1]]
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when "R"
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[start_position[0] + 1, start_position[1]]
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end.map{ |pos| pos.clamp(0, 2) }
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end
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end
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def reduce(array, initial_value)
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acc = initial_value
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array.each do |value|
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acc = yield(acc, value)
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end
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acc
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end
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input = STDIN.read.chomp
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direction_strings = input.split
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KEYPAD = [[ 1, 2, 3 ],
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[ 4, 5, 6 ],
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[ 7, 8, 9 ]]
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def keypad_digit(position)
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x, y = position
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KEYPAD[y][x]
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end
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digits = []
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direction_strings.inject([1, 1]) do |acc, x|
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y = DirectionString.new(x, acc).final_position
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digits << keypad_digit(y)
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y
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end
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puts "Part 1: #{digits.join}"
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