40 lines
749 B
Ruby
40 lines
749 B
Ruby
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# Quick 3-way sort version,
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# to protect against the worst case an array should be shuffled before,
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# see examples in test/quick3way_sort_test.rb
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class Quick3way
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def initialize(array)
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@array = array
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end
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def sort
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sort3way(@array, 0, @array.length - 1)
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@array
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end
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private
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def sort3way(array, lo, hi)
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return if lo >= hi
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pivot = array[lo]
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gt = hi
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lt = lo
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i = lo + 1
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while i <= gt
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if array[i] < pivot
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array[i], array[lt] = array[lt], array[i]
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lt += 1
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i += 1
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elsif array[i] > pivot
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array[i], array[gt] = array[gt], array[i]
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gt -= 1
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else
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i += 1
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end
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end
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sort3way(array, lo, lt - 1)
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sort3way(array, gt + 1, hi)
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end
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end
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