大顶堆 Java部分实现

转载自 https://blog.csdn.net/sunlei_secret/article/details/68486452

 

 

//java 大顶堆的简单实现
import java.util.Arrays;
public class Heap{
public void heapSort(int[] num){
  int n = num.length;
  for(int i = n/2;i>=0;i--){ //建堆,从n/2开始向上调整
    adjustHeap(num, i, n);
  }
  
for(int j=n-1;j>=0;j--){     swap(num,0, j); //交换开始和最后位置上的数字     adjustHeap(num, 0, j); //交换之后再调整堆   } }
public void adjustHeap(int[] num,int s,int n){ //由于根节点编号是从0开始的,所以其左子树是2*i+1   for(int i=s;i<n;){     int max = i;     if((2*i+1)<n&&num[2*i+1]>num[max]) max = 2*i+1;     if((2*i+2)<n&&num[2*i+2]>num[max]) max = 2*i+2;     if(max!=i){         swap(num,i,max);         i=max;     }else break;   } }
public void swap(int[] num,int i,int j){   int tem = num[i];   num[i] = num[j];   num[j] = tem; }
public static void main(String[] args) {   Heap heap = new Heap();   int[] num = new int[]{49,38,65,97,76,13,27,49};   heap.heapSort(num);   System.out.println(Arrays.toString(num));   } }

 

posted on 2019-03-03 10:47  wait_for_you  阅读(682)  评论(0编辑  收藏  举报

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