Sorting algorithms/Quicksort: Difference between revisions
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{{Sorting Algorithm}} |
{{Sorting Algorithm}} |
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In this task, the goal is to sort an array of elements using the [http://en.wikipedia.org/wiki/Quicksort Quicksort] algorithm. The elements must have a total order and the index of the array can be of any discrete type. For languages where this is not possible, sort an array of integers. |
In this task, the goal is to sort an array (or list) of elements using the [http://en.wikipedia.org/wiki/Quicksort Quicksort] algorithm. The elements must have a total order and the index of the array can be of any discrete type. For languages where this is not possible, sort an array of integers. |
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=={{header|Ada}}== |
=={{header|Ada}}== |
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dup 2 < if 2drop exit then |
dup 2 < if 2drop exit then |
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1- cells over + qsort ; |
1- cells over + qsort ; |
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=={{header|Haskell}}== |
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The famous two-liner, reflecting the underlying algorithm directly: |
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qsort [] = [] |
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qsort (x:xs) = qsort [y | y <- xs, y <= x] ++ [x] ++ qsort [y | y <- xs, y > x] |
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A more efficient version, doing only one comparison per element: |
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import Data.List |
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qsort [] = [] |
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qsort (x:xs) = qsort ys ++ x : qsort zs where (ys, zs) = partition (<= x) xs |
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==[[IDL]]== |
==[[IDL]]== |
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