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101 lines
2.0 KiB
101 lines
2.0 KiB
require "minitest"
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class Spiral
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def initialize
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@state = [0,0]
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end
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def each
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return enum_for(__method__) unless block_given?
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(1..Float::INFINITY).lazy
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.flat_map {|i| [i, i] }
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.zip(%i[r u l d].cycle)
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.flat_map {|n,d| Array.new(n, d) }
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.each do |dir|
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yield @state
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@state = @state.zip(
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case dir
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when :r
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[1, 0]
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when :u
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[0, 1]
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when :l
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[-1, 0]
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when :d
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[0, -1]
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end
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).map {|a,b| a + b }
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end
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end
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end
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class Grid
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def initialize
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@grid = Hash.new {|h,(x,y)|
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neighbors = [[-1, 1], [0, 1], [1, 1],
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[-1, 0], [1, 0],
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[-1,-1], [0,-1], [1,-1]]
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h[[x,y]] = neighbors
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.map {|i,j| [x+i,y+j] }
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.select {|i,j| h.has_key?([i,j]) }
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.map {|i,j| h[[i,j]] }
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.sum
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}
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@grid[[0,0]] = 1
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end
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def [](x,y)
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@grid[[x,y]]
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end
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end
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if $0 == __FILE__
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case ARGV.shift
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when "test"
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require "minitest/autorun"
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when "0"
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input = ARGF.read.to_i
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p Spiral.new.each.with_index.find {|_,i| i == input - 1 }.first.sum
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when "1"
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input = ARGF.read.to_i
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grid = Grid.new
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p Spiral.new.each.lazy.map {|x,y| grid[x,y] }.find {|value| value > input }
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end
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end
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class TestSpiral < Minitest::Test
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def test_spiral
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spiral = Spiral.new
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e = spiral.each
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assert_equal [0,0], e.next
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assert_equal [1,0], e.next
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assert_equal [1,1], e.next
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assert_equal [0,1], e.next
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assert_equal [-1,1], e.next
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assert_equal [-1,0], e.next
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assert_equal [-1,-1], e.next
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assert_equal [0,-1], e.next
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assert_equal [1,-1], e.next
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assert_equal [2,-1], e.next
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spiral = Spiral.new
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assert_equal [0,-2], spiral.each.with_index.find {|_,i| i == 22 }.first
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end
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end
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class TestGrid < Minitest::Test
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def test_grid
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grid = Grid.new
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assert_equal 1, grid[0,0]
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assert_equal 1, grid[1,0]
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assert_equal 2, grid[1,1]
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assert_equal 4, grid[0,1]
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assert_equal 5, grid[-1,1]
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assert_equal 10, grid[-1,0]
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end
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end
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