php快速排序的算法

1. function qsort(&$arr)
2. {
3. _quick_sort($arr, 0, count($arr) - 1);
4. }
6. /**
7. * 采用递归算法的快速排序。
8. *
9. * @param array $arr 要排序的数组
10. * @param int $low 最低的排序子段
11. * @param int $high 最高的排序字段
12. */
13. function _quick_sort(&$arr, $low, $high)
14. {
15. $low_data = $arr[$low];
16. $prev_low = $low;
17. $prev_high = $high;
18. while ($low {
19. while ($arr[$high] >= $low_data && $low $high--;
20. }
21. if ($low $arr[$low] = $arr[$high];
22. $low++;
23. }
24. while ($arr[$low] $low++;
25. }
26. if ($low $arr[$high] = $arr[$low];
27. $high--;
28. }
29. }
30. $arr[$low] = $low_data;
31. if ($prev_low _quick_sort($arr, $prev_low, $low);
32. }
33. if ($low + 1 _quick_sort($arr, $low + 1, $prev_high);
34. }
35. }
37. function quick_sort(&$arr)
38. {
39. $stack = array();
40. array_push($stack, 0);
41. array_push($stack, count($arr) -1);
42. while (!empty($stack)) {
43. $high = array_pop($stack);
44. $low = array_pop($stack);
45. $low_data = $arr[$low];
46. $prev_low = $low;
47. $prev_high = $high;
48. while ($low {
49. while ($arr[$high] >= $low_data && $low $high--;
50. }
51. if ($low $arr[$low] = $arr[$high];
52. $low++;
53. }
54. while ($arr[$low] $low++;
55. }
56. if ($low $arr[$high] = $arr[$low];
57. $high--;
58. }
59. }
60. $arr[$low] = $low_data;
61. if ($prev_low array_push($stack, $prev_low);
62. array_push($stack, $low);
63. }
64. if ($low + 1 array_push($stack, $low + 1);
65. array_push($stack, $prev_high);
66. }
67. }
68. }

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