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- # quicksort.awk --- Quicksort algorithm, with user-supplied
- # comparison function
- #
- # Arnold Robbins, arnold@skeeve.com, Public Domain
- # January 2009
- # quicksort --- C.A.R. Hoare's quicksort algorithm. See Wikipedia
- # or almost any algorithms or computer science text.
- #
- # Adapted from K&R-II, page 110
- function quicksort(data, left, right, less_than, i, last)
- {
- if (left >= right) # do nothing if array contains fewer
- return # than two elements
- quicksort_swap(data, left, int((left + right) / 2))
- last = left
- for (i = left + 1; i <= right; i++)
- if (@less_than(data[i], data[left]))
- quicksort_swap(data, ++last, i)
- quicksort_swap(data, left, last)
- quicksort(data, left, last - 1, less_than)
- quicksort(data, last + 1, right, less_than)
- }
- # quicksort_swap --- helper function for quicksort, should really be inline
- function quicksort_swap(data, i, j, temp)
- {
- temp = data[i]
- data[i] = data[j]
- data[j] = temp
- }
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