請問這題Quick Sort步驟是什麼

Can I answer this in English?

2009-04-19 23:18:01 補充：
function quicksort(array)
var list less, greater
if length(array) ≤ 1
return array
select and remove a pivot value pivot from array
for each x in array
if x ≤ pivot then append x to less
else append x to greater
return concatenate(quicksort(less), pivot, quicksort(greater))

To find the pivot, use median of 3. Median of median is the best but will be complicated. median = first element, last element and
(int) (first + last) / 2 or first element if array < 3

1 pivot is median( 1, 7, 6 ) = 6
2 1, 2, 3, 5, 4 goes to less and 8, 7 goes to grea
3 quicksort(less: 1, 2, 3, 5, 4):
4 pivot is median(1, 3, 4) = 3
5 1, 2 goes to less and 5, 4, 6 goes to greater
6 quicksort(less: 1, 2):
7 pivot is median(1, 2) = 1
8 NULL goes to less and 2 goes to greater
9 quicksort(less: NULL):
10 return NULL
11 quicksort(greater: 2):
12 return 2
13 return concatenate(NULL, 1, 2)
14 quicksort(greater: 5, 4, 6):
15 pivot is median(5, 4, 6) = 5
16 4 goes to less and 6 goes to greater
17 quicksort(less: 4):
18 return 4
19 quicksort(greater: 6):
20 return 6
21 concatenate(4, 5, 6)
22 concatenate(1, 2, 3, 4, 5, 6)
23 quicksort(greater: 8, 7):
24 pivot is median(8, 7) = 8
25 7 goes to less, NULL goes to greater
26 quicksort(less: 7):
27 return 7
28 quicksort(greater: NULL)
29 return NULL
30 concatenate(7, 8, NULL)
31 concatenate(1, 2, 3, 4, 5, 6, 7, 8)

The quicksort algorithm is from wiki. I have added median of 3 to it.
Note that the algorithm uses about 31 steps to sort in this case. You can try some other arrays to convince yourself the sort is O(nlogn).

yes you can
please tell me the answer, THX