6 lines
144 B
Ruby
6 lines
144 B
Ruby
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def fib(n)
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raise RangeError, "fib of negative" if n < 0
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Hash.new { |fib2, m|
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fib2[m] = (m < 2 ? m : fib2[m - 1] + fib2[m - 2]) }[n]
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end
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