BuildMaxHeap 

 1//O(nlogn)
　　　public class BuildMaxHeap {
 2     
 3     private static int[] input = new int[] { 4, 1, 3, 2, 16, 9, 10, 14, 8, 7 }; 
 4     private static int heapSize = input.length; 
 5     
 6     public static void buildMaxHeap(){
 7         for(int i=heapSize/2;i>0;i--){
 8             maxHeapify(input, i);
 9         }
10     }
11 
12     public static void maxHeapify(int[] a,int index){
13         int l=index*2;
14         int r=l+1;
15         int largest;
16         if(l<=heapSize && a[l-1]>a[index-1]){
17             largest=l;
18         }
19         else{
20             largest=index;
21         }
22         if(r<=heapSize && a[r-1]>a[largest-1]){
23             largest=r;
24         }
25         if(largest != index){
26             int temp=a[index-1];
27             a[index-1]=a[largest-1];
28             a[largest-1]=temp;
29             maxHeapify(a,largest);
30         }
31         
32     }
33     
34     public static void printArray(int[] a){
35         for(int i = 0;i < a.length;i++){
36             System.out.print(a[i]+" ");
37         }
38     }
39     
40     public static void main(String[] args) {
41         // TODO Auto-generated method stub
42         buildMaxHeap();
43         printArray(input);
44     }
45 
46 }

 

posted on 2013-03-29 23:52  melotang  阅读(400)  评论(0)    收藏  举报