基于算法导论6.5用最大堆实现的优先队列(C++)

// algorithms.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "iostream"
using std::cout;
using std::endl;
int heapSize;
const int arraySize = 10;
void maxHeapIFY(int *,int);
void buildHeap(int *,int length);
void swap(int &, int &);
int heapMaximum(int *);
int HeapExtractMax(int *);
void heapIncreaseKey(int *, int, int);
void maxHeapInsert(int *a, int key);
int main()
{
int a[10] = { 121, 22, 13, 34, 53, 62, 71, 48, 59, 104};

buildHeap(a, arraySize);
HeapExtractMax(a);
maxHeapInsert(a, 1);
for (size_t i = 0; i < arraySize; i++)
{
cout << a[i] << " ";
}

return 0;
}
void buildHeap(int *a,int length){
heapSize = length - 1;
for (int i = length>>1; i >= 0; i--)
{
maxHeapIFY(a, i);
}
}
void maxHeapIFY(int *a,int i){
int l = (i << 1) + 1;
int r = (i << 1) + 2;
int largest;
if (l <= heapSize && a[i] < a[l])
{
largest = l;
}
else
{
largest = i;
}
if (r <= heapSize && a[largest] < a[r])
{
largest = r;
}
while (largest!=i)
{
swap(a[largest], a[i]);
i = largest;
int l = (i << 1) + 1;
int r = (i << 1) + 2;
if (l <= heapSize && a[i] < a[l])
{
largest = l;
}
else
{
largest = i;
}
if (r <= heapSize && a[largest] < a[r])
{
largest = r;
}
}
}
void swap(int &i, int &j){
int temp = i;
i = j;
j = temp;
}

int heapMaximum(int *a)
{
return a[1];
}

int HeapExtractMax(int *a)
{
if (heapSize < 0)
{
cout << "heap underflow\n 堆下溢" << endl;
return -1;
}
else
{
int max = a[0];
a[0] = a[heapSize];
heapSize = heapSize - 1;
maxHeapIFY(a, 0);
return max;
}
}

void heapIncreaseKey(int *a, int i, int key)
{
if (key < a[i])
{
cout << "new key is smaller than current key\n 新关键字小于当前关键字" << endl;
return;
}
a[i] = key;
int parent = i % 2 == 0 ? (i >> 1) - 1 : i >> 1;  //找父节点，由于是根节点是0开始，所以当节点是单数时父节点是当节点除以2，当节点是双数时父节点是当前节点除以2减1
while (i>0 && a[parent] < a[i])
{
swap(a[parent], a[i]);
i = parent;
parent = i % 2 == 0 ? (i >> 1) - 1 : i >> 1;
}
}

void maxHeapInsert(int *a, int key)
{
if (heapSize == arraySize - 1)
{
cout << "heap size is larger than array size\n堆大小比数组长度大" << endl;
return;
}
heapSize = heapSize + 1;
a[heapSize] = -100000000;
heapIncreaseKey(a, heapSize, key);
}