Java 堆排序

 1 public class HeapSort {
 2     public static void main(String[] args) {
 3         int[] a = new int[]{6, 2, 8, 3, 5, 1, 8, 6, 54, 64, -1, 2, 4, 4, 67};
 4         heapSort(a);
 5         System.out.println();
 6     }
 7 
 8     static void heapSort(int[] a) {
 9         int bounds = a.length;
10         for (int i = bounds - 1; i >= 0; i--) maxHeap(i, bounds, a);
11         while (bounds > 0) {
12             int t = a[0];
13             a[0] = a[bounds - 1];
14             a[bounds - 1] = t;
15             bounds--;
16             for (int i = bounds - 1; i >= 0; i--) maxHeap(i, bounds, a);
17         }
18     }
19 
20     static void maxHeap(int r, int bounds, int[] a) {
21         int left = (r + 1) * 2 - 1, right = left + 1;
22         if (left >= bounds) return;
23         if (right >= bounds) {
24             if (a[left] > a[r]) {
25                 int t = a[left];
26                 a[left] = a[r];
27                 a[r] = t;
28                 maxHeap(left, bounds, a);
29             }
30             return;
31         }
32         if (a[left] > a[right]) {
33             int t = a[left];
34             a[left] = a[right];
35             a[right] = t;
36         }
37         if (a[right] > a[r]) {
38             int t = a[right];
39             a[right] = a[r];
40             a[r] = t;
41             maxHeap(right, bounds, a);
42             return;
43         }
44     }
45 }