17 lines
210 B
Ruby
17 lines
210 B
Ruby
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def factorial(n)
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i = 1
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while (n > 0)
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i *= n
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n -= 1
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end
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i
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end
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def combination(n, k)
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factorial(n) / (factorial(k) * factorial(n-k))
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end
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def lattice_paths(size)
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combination(2*size, size)
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end
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