/
Quicksort.java
61 lines (39 loc) · 916 Bytes
/
Quicksort.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
package playground.dsa.quicksort;
import playground.dsa.common.SortingAlgorithm;
public class Quicksort implements SortingAlgorithm {
@Override
public int[] sort(int[] ints) {
quicksort(ints, 0, ints.length);
return ints;
}
public void quicksort(int[] a, int p, int r) {
if (p < r - 1) {
int q = partition(a, p, r);
quicksort(a, p, q);
quicksort(a, q, r);
}
}
private int partition(int[] a, int p, int r) {
int pivot = a[r - 1];
int i = p - 1;
for(int j = p; j < r - 1; j ++) {
if (a[j] <= pivot) {
i = i + 1;
//
// swap i, j
//
int tmp = a[i];
a[i] = a[j];
a[j] = tmp;
}
}
//
// swap i + 1 and the pivot
//
int q = i + 1;
int tmp = a[q];
a[q] = a[r - 1];
a[r - 1] = tmp;
return q;
}
}