堆用作优先队列

#include<iostream>
using namespace std;

//把a[i]中的数值增加到新的值key
void Heap_Increase_Key(int a[], int i, int key)
{
    if (key < a[i])
        exit(1);
    a[i] = key;
    while (i>1&&a[i/2]<a[i])
    {
        int t = a[i];
        a[i] = a[i / 2];
        a[i / 2] = t;
        i = i / 2;
    }
}




//插入一个新的值key到堆里
void Max_Heap_Insert(int a[], int key,int size)
{
    size++;
    a[size] = -100000;//此处应取到尽量小的数
    Heap_Increase_Key(a, size, key);
}


//取走最大数
int Heap_Extract_Max(int a[],int max,int size)
{
    int n = size;
    if (n < 1)
        exit(1);
    int max = a[1];
    a[1] = a[n];
    size--;
    Max_Heapify(a, 1);//Max_Heapify函数用于堆的修复
    return max;
}