93 lines
1.6 KiB
Ruby
93 lines
1.6 KiB
Ruby
# The Great Computer Language Shootout
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# http://shootout.alioth.debian.org/
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#
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# contributed by Gabriele Renzi
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class PiDigitSpigot
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def initialize()
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@z = Transformation.new 1,0,0,1
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@x = Transformation.new 0,0,0,0
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@inverse = Transformation.new 0,0,0,0
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end
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def next!
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@y = @z.extract(3)
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if safe? @y
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@z = produce(@y)
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@y
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else
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@z = consume @x.next!()
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next!()
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end
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end
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def safe?(digit)
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digit == @z.extract(4)
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end
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def produce(i)
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@inverse.qrst(10,-10*i,0,1).compose(@z)
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end
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def consume(a)
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@z.compose(a)
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end
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end
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class Transformation
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attr_reader :q, :r, :s, :t
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def initialize(q, r, s, t)
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@q,@r,@s,@t,@k = q,r,s,t,0
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end
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def next!()
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@q = @k = @k + 1
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@r = 4 * @k + 2
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@s = 0
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@t = 2 * @k + 1
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self
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end
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def extract(j)
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(@q * j + @r) / (@s * j + @t)
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end
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def compose(a)
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self.class.new( @q * a.q,
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@q * a.r + r * a.t,
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@s * a.q + t * a.s,
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@s * a.r + t * a.t
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)
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end
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def qrst *args
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initialize *args
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self
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end
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end
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WIDTH = 10
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n = 2_500 # Integer(ARGV[0])
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j = 0
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digits = PiDigitSpigot.new
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while n > 0
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if n >= WIDTH
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WIDTH.times {print digits.next!}
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j += WIDTH
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else
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n.times {print digits.next!}
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(WIDTH-n).times {print " "}
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j += n
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end
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puts "\t:"+j.to_s
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n -= WIDTH
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end
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