最大堆排序

package algorith;

public class Heap {

/**

* @param args

* 最大堆排序

*/

public static void main(String[] args) {

Heap h = new Heap ();

int[] a ={3,4,5,2,1,6,7};

h.initialization(a);

for(int b :a){

System.out.print(b+" ");

}

System.out.println();

h.sort(a);

for(int b :a){

System.out.print(b+" ");

}

}

public  void initialization(int[] array){

int len = array.length;

for(int i =len/2-1 ;i>=0;i--){

maxHeap(array,i,len);

}

}

public static void maxHeap(int[] array , int i ,int length){

int index = i ;

if((2*i+1 <=length-1 )&&(array[2*i+1]>array[i])){

index = 2*i+1;

}

if((2*i+2 <=length-1 )&&(array[2*i+2]>array[index])){

index = 2*i+2;

}

if(index != i){

swap(array,index,i);

maxHeap(array,index,length);

}

}

//把第一个值与最后一个交换，排除最后一个，对其他的树操作！

public void sort(int[] array){

int len = array.length;

for(int i = array.length-1; i>=0;i--){

swap(array,0,i);

len-=1;

maxHeap(array,0,len);

}

}

   

public static void swap(int[] array , int i , int j){

int temp = array[i];

array[i] = array[j];

array[j] = temp;

}

}