2.堆排序

#include "string"
#include "vector"
#include "time.h"
typedef std::basic_string<TCHAR> tstring;
typedef std::vector<int> IntVec;

// iIndexAdjust 从0计数.... left = 2i+1;right = 2i+2
// 最后一个非叶子节点  (iHeapTreeSize - 2) / 2
// iHeapTreeSize 无序堆大小(无序区节点数)
void HeapifyMax(IntVec & iHeapTree,int const iIndexAdjust,int const iHeapTreeSize)
{
	if (iIndexAdjust > (iHeapTreeSize - 2) / 2)//只针对非叶子节点
		return;

	int iIndexGreater = iIndexAdjust;
	
	int child = 2 * iIndexAdjust + 1;
	if (child < iHeapTreeSize && iHeapTree[child] > iHeapTree[iIndexGreater])
		iIndexGreater = child;

	child = 2 * iIndexAdjust + 2;
	if (child < iHeapTreeSize && iHeapTree[child] > iHeapTree[iIndexGreater])
		iIndexGreater = child;

	if (iIndexAdjust == iIndexGreater)
		return;
	std::swap(iHeapTree[iIndexAdjust], iHeapTree[iIndexGreater]);

	HeapifyMax(iHeapTree, iIndexGreater, iHeapTreeSize);//重新修正子树

}
// 从最后一个非叶子节点开始构建
void HeapBuild(IntVec & iHeapTree){

	for (int i = (iHeapTree.size() - 2) / 2; i >= 0; i--){
		HeapifyMax(iHeapTree, i,iHeapTree.size());
	}
}
void HeapSort(IntVec & iHeapTree){

	for (int i = iHeapTree.size() - 1; i >= 0; i--)
	{
		std::swap(iHeapTree[0], iHeapTree[i]);
		HeapifyMax(iHeapTree, 0, i); // 最后一个参数 HeapBuild时是 iHeapTree.size(),交换一次根,少一个节点
	}
}
void HeapPrint(IntVec & iHeapTree){

	for (auto i:iHeapTree){
		printf("%d ", i);
	}
	printf("\n");
}
int _tmain(int argc, _TCHAR* argv[])
{
	srand((unsigned int)time(0));
	IntVec ints;
	for (int i = 0; i < 20; i++){

		ints.push_back(rand() % 100);
	}
	printf("arr init\n");HeapPrint(ints);
	
	HeapBuild(ints);
	printf("arr after build \n"); HeapPrint(ints);

	HeapSort(ints);

	printf("arr after sort \n"); HeapPrint(ints);
	return 0;
}

　　

arr init
74 51 18 91 59 88 48 16 76 23 17 64 52 82 30 67 52 5 93 12
arr after build
93 91 88 76 59 64 82 67 74 23 17 18 52 48 30 16 52 5 51 12
arr after sort
5 12 16 17 18 23 30 48 51 52 52 59 64 67 74 76 82 88 91 93