JAVA算法起步之堆排序实例

public class HeapSort {
 private int getLeft(int i){
  return 2*i+1;
 }
 private int getRight(int i){
  return 2*i+2;
 }
 public void maxheap(int[] heap,int loc,int size){
  int l=getLeft(loc);
  int r=getRight(loc);
  int largest=loc;
  if(l<size&&heap[l]>heap[loc]){
   largest=l;
  }
  if (r<size&&heap[r]>heap[largest]) {
   largest=r;
  }
  if(largest!=loc){
   int cache=heap[loc];
   heap[loc]=heap[largest];
   heap[largest]=cache;
   maxheap(heap, largest, size);
  }
 }
 public void buildheap(int[] heap){
  for(int i=heap.length/2;i>=0;i--){
   maxheap(heap, i, heap.length);
  }
 }
 public void sort(int[] heap){
  buildheap(heap);
  for(int i=heap.length-1;i>1;i--){
   int cache=heap[0];
    heap[0]=heap[i];
    heap[i]=cache;
   maxheap(heap, 0,i );
  }
  int cache=heap[0];
   heap[0]=heap[1];
   heap[1]=cache;

 }

 public static void main(String[] args) {
  int[] heap=new int[]{4,1,5,3,7,12,65,7};
  HeapSort hs=new HeapSort();
  hs.sort(heap);
  for (int i = 0; i < heap.length; i++) {
   System.out.println(heap[i]);
  }
 }
}