Commit 84543a02b292c5be658f2b191377091affc4ef3d
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quicksort
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quicksort.go
| File was created | 1 | package webutility | |
| 2 | |||
| 3 | type QSortDirection int | ||
| 4 | |||
| 5 | const ( | ||
| 6 | QSortAscending = 0 | ||
| 7 | QSortDescending = 1 | ||
| 8 | ) | ||
| 9 | |||
| 10 | // QuickSortable is an interface for quicksorting slices. | ||
| 11 | type QuickSortable interface { | ||
| 12 | Swap(i, j int) | ||
| 13 | Compare(i, j int) int | ||
| 14 | Len() int | ||
| 15 | } | ||
| 16 | |||
| 17 | // Quicksort quicksorts que. | ||
| 18 | func Quicksort(que QuickSortable, low, high int, dir QSortDirection) { | ||
| 19 | if low >= high { | ||
| 20 | return | ||
| 21 | } | ||
| 22 | |||
| 23 | if dir != QSortAscending && dir != QSortDescending { | ||
| 24 | return | ||
| 25 | } | ||
| 26 | |||
| 27 | index := partition(que, low, high, dir) | ||
| 28 | Quicksort(que, low, index-1, dir) | ||
| 29 | Quicksort(que, index+1, high, dir) | ||
| 30 | } | ||
| 31 | |||
| 32 | func partition(que QuickSortable, low, high int, dir QSortDirection) int { | ||
| 33 | i := low - 1 | ||
| 34 | for j := low; j <= high-1; j++ { | ||
| 35 | if dir == QSortAscending { | ||
| 36 | if que.Compare(j, high) == -1 { | ||
| 37 | i++ | ||
| 38 | que.Swap(i, j) | ||
| 39 | } | ||
| 40 | } else if dir == QSortDescending { | ||
| 41 | if que.Compare(j, high) == 1 { | ||
| 42 | i++ | ||
| 43 | que.Swap(i, j) | ||
| 44 | } | ||
| 45 | } | ||
| 46 | } | ||
| 47 | que.Swap(i+1, high) | ||
| 48 | return i + 1 | ||
| 49 | } | ||
| 50 |