网络营销成餐饮业市场新高地

堆排序有以下需要注意的：

 

parent=n/2

left = 2 * n;

right = 2 * n + 1;

 

对某一个节点进行最大堆化

maxHeap

 

 

然后构造堆

buildHeap

 

最后是堆排序

heapSort

 

具体代码：

package com.taobao.saleengine.core.util;

public class HeapSort2 {

private static int left(int i) { return i * 2;}
private static int right(int i) { return i * 2 + 1;}
private static void maxHeap(int[] a, int i, int length) {
int l = left(i);
int r = right(i);

int largest = i;

while(l<length && r<length) {
if(a[l]>a[largest]) {
largest = l;
}
if(a[r] > a[largest]) {
largest = r;
}

if(largest != i) {
int temp = a[largest];
a[largest] = a[i];
a[i] = temp;
i = largest;
l = left(i);
r = right(i);
} else {
break;
}
}
}

private static void buildHeap(int a[], int length) {
int start = length / 2 + 1;
for(int i=start;i>=0;i--) {
maxHeap(a, i, length);
}
}

private static void heapSort(int a[]) {
int length = a.length;
buildHeap(a, length);
while(length >= 1) {
int temp = a[0];
a[0] = a[length - 1];
a[length - 1] = temp;
maxHeap(a, 0, length - 1);
length--;
}
}
public static void printline(String s, int[] v) {
System.out.println(s + toString(v));
}

public static String toString(int a[]) {
StringBuilder s = new StringBuilder();
for (int x : a)
s.append(" ").append(x);
return s.toString();
}
public static void main(String[] args) {
int a[] = new int[] { 16, 4, 10, 14, 7, 9, 3, 2, 8, 1};
heapSort(a);
printline("sorted ", a);
}
}