堆排序

Posted 2020-10-05 StringBuilder

 1 public class Solution
 2 {
 3     public void heapSort(int[] data)
 4     {
 5         heapBuild(data);
 6         
 7         for(int i = data.length - 1; i > 0; i --)
 8         {
 9             exchange(data, i, 0);
10             
11             heapAdjust(data, 0, i - 1);
12         }
13     }
14     
15     public void heapBuild(int[] data)
16     {
17         for(int i = (data.length + 1) / 2 - 1; i >= 0; i --)
18         {
19             heapAdjust(data, i, data.length - 1);
20         }
21     }
22     
23     public void heapAdjust(int[] data, int startPosition, int bottomPosition)
24     {
25         if(startPosition > (bottomPosition + 1) / 2 - 1)
26         {
27             return;
28         }
29         
30         int leftChildIndex = 2 * startPosition + 1;
31         
32         int rightChildIndex = 2 * startPosition + 2;
33         
34         int maxValueIndex = startPosition;
35         
36         if(data[leftChildIndex] > data[maxValueIndex])
37         {
38             maxValueIndex = leftChildIndex;
39         }
40         
41         if(rightChildIndex <= bottomPosition)
42         {
43             if(data[rightChildIndex] > data[maxValueIndex])
44             {
45                 maxValueIndex = rightChildIndex;
46             }
47         }
48         
49         if(maxValueIndex != startPosition)
50         {
51             exchange(data, maxValueIndex, startPosition);
52             
53             heapAdjust(data, maxValueIndex, bottomPosition);
54         }
55     }
56     
57     public void exchange(int[] data, int m, int n)
58     {
59         int memory = data[m];
60         
61         data[m] = data[n];
62         
63         data[n] = memory;
64     }
65     
66 }