java算法----排序----（7）堆排序

 1 package log;
 2 
 3 import java.util.Arrays;
 4 
 5 public class Test4 {
 6     /**
 7      * 堆排序
 8      * 
 9      * @param args
10      */
11     public static void main(String[] args) {
12         int arr[] = { 49, 20, 36, 51, 18, 94, 61, 31, 50 };
13 
14         // 循环输出该数组内容
15         System.out.println("排序之前：");
16         for (int a : arr) {
17             System.out.print(a + "	");
18         }
19         System.out.println();
20 
21         int arrlength = arr.length;
22 
23         // 循环建堆
24         for (int i = 0; i < arrlength - 1; i++) {
25             build(arr, arrlength - 1 - i);
26             swap(arr, 0, arrlength - 1 - i);
27             System.out.println(Arrays.toString(arr));
28         }
29 
30         // 循环输出该数组内容
31         System.out.println("排序之后：");
32         for (int a : arr) {
33             System.out.print(a + "	");
34         }
35         System.out.println();
36 
37     }
38 
39     private static void build(int[] data, int lastIndex) {
40         for (int i = (lastIndex - 1) / 2; i >= 0; i--) {
41             int k = i;
42             while (k * 2 + 1 <= lastIndex) {
43                 int bigIndex = 2 * k + 1;
44                 if (bigIndex < lastIndex) {
45                     if (data[bigIndex] < data[bigIndex + 1]) {
46                         bigIndex++;
47                     }
48                 }
49 
50                 if (data[k] < data[bigIndex]) {
51                     swap(data, k, bigIndex);
52                     k = bigIndex;
53                 } else {
54                     break;
55                 }
56 
57             }
58         }
59     }
60 
61     private static void swap(int[] data, int i, int j) {
62         int temp = data[i];
63         data[i] = data[j];
64         data[j] = temp;
65     }
66 
67 }
下面是控制台的输出