Heap Sort
// HeapSort.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
void DirectSelectSort(int* a, int iLen);
void HeapSort(int* a, int iLen);
void FilterDown(int* a, int iStart, int iEnd);
void PrintArray(int a[], int iLen);
void Swap(int* a, int index1, int index2);
int _tmain(int argc, _TCHAR* argv[])
{
int arrayToSort[] = {20, 7, 3, 4, 25, 15, 29, 12, 4, 1};
int n = sizeof(arrayToSort)/sizeof(int);
PrintArray(arrayToSort, n);
HeapSort(arrayToSort, n);
PrintArray(arrayToSort, n);
return 0;
}
void HeapSort(int* a, int iLen)
{
if(a==NULL||iLen<=0)
return;
// Initialize to a heap
int i;
for(i=(iLen-2)/2;i>=0;i--)
{
FilterDown(a,i,iLen-1);
}
for(i=iLen-1;i>=1;i--)
{
Swap(a, i, 0);
FilterDown(a,0,i-1);
}
}
void FilterDown(int* a, int iStart, int iEnd)
{
if(iStart>=iEnd) return;
int iParent = iStart;
int iChild = iParent*2+1;
while(iChild<=iEnd)
{
if(iChild<iEnd)
if(a[iChild]<a[iChild+1])
iChild += 1;
if(a[iParent]<a[iChild])
{
Swap(a,iParent, iChild);
iParent = iChild;
iChild = 2*iChild +1;
}
else
{
break;
}
}
}
void Swap(int* a, int index1, int index2)
{
if(index1!=index2&&a!=NULL)
{
int temp = a[index1];
a[index1] = a[index2];
a[index2] = temp;
}
}
void PrintArray(int a[], int iLen)
{
for(int i=0; i< iLen; i++)
{
std::cout<<a[i]<<' ';
}
std::cout<<std::endl;
}
