C++、C#、java算法学习日记07----堆排序（HeapSort）

C++实例：

#include<iostream>
#include<vector>
#include<ctime>

using namespace std;
//调整堆
void HeapAdjust(vector<int> &array,int i,int nLength)
{
int Child;
for(;2*i+1<nLength;i=Child)
{
Child=2*i+1;  //左孩子下标 Child+1 右孩子下标
if(Child+1<nLength&&array[Child]<array[Child+1])
{  Child++;}
if(array[i]<array[Child]) //保证父节点大于左右孩子
{
swap(array[i],array[Child]);
}
else
{break;}
}

}
//首尾交换再调整
void HeapSort(vector<int> &array,int Length)
{
for(int i=(Length/2-1);i>=0;i--) //第一次调整为大根堆，需要对所有的节点都比较
{
HeapAdjust(array,i,Length);
}
for(int j=Length-1;j>0;j--)
{
swap(array[j],array[0]);//交换

HeapAdjust(array,0,j); //不是第一次调整，只需要局部调整就行了
}

}
void main()
{
vector<int> array;
clock_t start,end;
for(int i=0;i<10000;i++) //将10000个数放入容器
{
array.push_back(rand());
}
int Length=array.size(); //计算长度
start=clock();//开始时间

HeapSort(array,Length); //堆排序
end=clock();//结束时间
//输出前十个数
for(int i=0;i<10;i++)
{
cout<<array[i]<<"  ";
}
cout<<endl;
cout<<"堆排序用时："<<end-start<<" 毫秒"<<endl;
}

C#实例：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics; //要添加这个引用否则没有Stopwatch

namespace HeapSort2
{
class Sort
{ //调整堆
public void HeapAdjust(List<int> array, int i, int nLength)
{
int Child, temp;
for (; 2 * i + 1 < nLength; i = Child)
{
Child = 2 * i + 1;
if (Child + 1 < nLength && array[Child + 1] > array[Child])
{ Child++; }
if (array[i] < array[Child])
{
temp = array[i];
array[i] = array[Child];
array[Child] = temp;
}
else
{ break; }

}
}
//首尾交换再调整
public void HeapSort(List<int> array)
{
int temp;
for (int i = array.Count / 2 - 1; i >= 0; i--)
{
HeapAdjust(array, i, array.Count);
}
for (int j = array.Count - 1; j > 0; j--)
{
temp = array[0];
array[0] = array[j];
array[j] = temp;
HeapAdjust(array, 0, j);
}
}
static void Main(string[] args)
{
List<int> array = new List<int>();
Random r = new Random();
Stopwatch watch = new Stopwatch();
for (int i = 0; i < 10000; i++)
{
array.Add(r.Next(1, 100000));
}
Console.WriteLine("排序前前十个元素为：" + String.Join(" ", array.Take(10).ToList()));
Sort sorter = new Sort();
watch.Start(); //开始计时
sorter.HeapSort(array); //堆排序
watch.Stop(); //结束计时
Console.WriteLine("排序后前十个元素为：" + String.Join(" ", array.Take(10).ToList()));
Console.WriteLine("堆排序用时：" + watch.ElapsedMilliseconds);
}
}
}

java实例：

package Sort;
import java.util.*;
public class Sort6 {
public void HeapAdjust(List<Integer> array,int i,int nLength){
int temp,Child;
for(;2*i+1<nLength;i=Child){
Child=2*i+1;
if(Child+1<nLength&&array.get(Child)<array.get(Child+1)){
Child++;
}
if(array.get(i)<array.get(Child)){
temp=array.get(i);
array.set(i, array.get(Child));
array.set(Child, temp);
}
else{
break;
}
}

}
public void HeapSort(List<Integer> array){
int temp;
for(int i=array.size()/2-1;i>=0;i--){
HeapAdjust(array,i,array.size());
}
for(int j=array.size()-1;j>0;j--){
temp=array.get(0);
array.set(0,array.get(j));
array.set(j, temp);
HeapAdjust(array,0,j);
}
}

public static void main(String[] args) {
List<Integer> array = new ArrayList<Integer>();
for(int i=0;i<10000;i++){
array.add(new Random().nextInt(100000));
}
System.out.print("排序前前十个元素为：");
for(int i=0;i<10;i++){
System.out.print(array.get(i)+" ");
}
System.out.println();
Sort6 sorter =new Sort6();
long time_start=System.currentTimeMillis();//开始时间
sorter.HeapSort(array);
long time_stop=System.currentTimeMillis();//开始时间
System.out.print("排序后前十个元素为：");
for(int i=0;i<10;i++){
System.out.print(/*i==0?"\n排序后前十个元素为：":" "+*/array.get(i)+" ");
}
System.out.print("\n"+"堆排序用时："+(time_stop-time_start));

}

}