heap实现的最大优先队列

#include<iostream>
#include<stdlib.h>
#include<time.h>
using namespace std;

#define LEFT(i) 2*(i)
#define RIGHT(i) 2*(i)+1
#define PARENT(i) (i)/2

int size = 15;

void h_swap(int &a,int &b)
{
	int t=a;
	a=b;
	b=t;
}

void max_heapfy(int a[],int i)
{
	int max;
	int l;
	int r;

	l=LEFT(i);
	r=RIGHT(i);

	if(l<=size&&a[l]>a[i]){
		max=l;
	}
	else{
		max=i;
	}

	if(r<=size&&a[r]>a[max]){
		max = r;
	}

	if(max!=i)
	{
		h_swap(a[max],a[i]);
		max_heapfy(a,max);
	}
}

void BuildHeap(int a[])
{
	for(int i=size/2;i>=1;i--)
	{
		max_heapfy(a,i);
	}
} 

void print(int a[],int n)
{
	int i=1;
	while(i<=n)
	{
		cout<<a[i]<<" ";
		i++;
	}
	cout<<endl;
}

int Heap_max(int a[])
{
	return a[1];
}

int Heap_extract_max(int a[])
{
	if(size<1){
		cout<<"heap is NULL"<<endl;
		exit(-1);
	}
	int max;
	max=a[1];
	h_swap(a[1],a[size]);
	size--;
	max_heapfy(a,1);
	
	return max;
}

void heap_increase_key(int a[],int i,int key)
{
	if(key<a[i]){
		cout<<"key is smaller than a[i]"<<endl;
		exit(-1);
	}

	a[i] = key;
	while(i>1&&PARENT(i)<a[i])
	{
		h_swap(a[i],a[PARENT(i)]);
		i=PARENT(i);
	}
}

void max_heap_insert(int a[],int key)
{
	size=size+1;
	a[size] = 0xffffffff;
	heap_increase_key(a,size,key);
}

int main()
{
	int a[101];

	srand(time(0));
	for(int i=1;i<=size;i++)
	{
		a[i]=rand()%100*size;
	}

	BuildHeap(a);
	print(a,size);

	cout<<Heap_extract_max(a)<<endl;
	print(a,size-1);

	heap_increase_key(a,10,100000);
	print(a,size);

	max_heap_insert(a,100);
	print(a,size);

	return 0;
}