Priority_Queue C++

优先队列:

是计算机科学中的一类抽象数据类型。优先队列中的每个元素都有各自的优先级，优先级最高的元素最先得到服务；优先级相同的元素按照其在优先队列中的顺序得到服务。优先队列往往用堆来实现。

#pragma once
#include<vector>
#include<stdexcept>//runtime_error
#include<iostream>
#include"HEAPSORT.h"

int Heap_Maximum(std::vector<int>& A)
{
    return A[0];
}


//取最大值并删除
int Heap_Extract_Max(std::vector<int>& A)
{
    heap_size = A.size() - 1;
    Build_Max_Heap(A);
    /*
    try
    {
        if (heap_size < 0)
            throw std::runtime_error("heap underflow");
    }
    catch (std::runtime_error err)
    {
        std::cout << err.what()
            << "
 Try Again? Enter y or n" << std::endl;
        char c;
        std::cin >> c;
        if (!std::cin || c == 'n')
            return -1;
    }
    */
    if (heap_size < 0)
        throw std::runtime_error("heap underflow");
    int max = A[0];
    A[0] = A[heap_size];
    --heap_size;
    Max_Heapify(A, 0);
    return max;
}
//改变(变大)节点里面的值
void Heap_Increase_Key(std::vector<int>& A, int& i, const int& key)
{
    if (key < A[i])
        throw std::runtime_error("new key is small than current key");
    A[i] = key;
    //保持最大堆
    while (i > 0 && A[parent(i)] < A[i])
    {
        std::swap(A[i], A[parent(i)]);
        i = parent(i);
    }
}
//在末尾处插入键值
void Max_Heap_Insert(std::vector<int>& A, const int& key)
{
    ++heap_size;
    A[heap_size] = INT_MIN;
    Heap_Increase_Key(A, heap_size, key);
}

main.cpp

#include<iostream>
#include<iterator> //ostream_iterator
#include"PRIORITY_QUEUE.h"
using namespace std;
void print(vector<int>& v)
{
    ostream_iterator<int> out_iter(cout, " ");
    copy(v.begin(), v.end(), out_iter);
}
void Priority_Queue()
{
    vector<int> v = { 4,1,3,2,16,9,10,14,8,7 };
    print(v);
    cout << endl;
    cout << Heap_Extract_Max(v) << endl;
    Max_Heap_Insert(v, 15);
    cout<<Heap_Maximum(v) << endl;
    HeapSort(v);
    print(v);
}
int main()
{
    Priority_Queue();
}