堆——优先队列

/*
挑战程序设计竞赛——第2版
P73
*/
#include<iostream>
#include<queue>
#include<cstdio>
#define MAX_N 100
using namespace std;

int heap[MAX_N], sz = 0;

void push(int x)
{
    //自己结点的编号
    int i = sz++;

    while (i > 0)
    {
        int p = (i - 1) / 2;

        //如果没有大小颠倒则退出
        if (heap[p] <= x)break;

        heap[i] = heap[p];
        i = p;
    }

    heap[i] = x;
}

int pop()
{
    int ret = heap[0];

    int x = heap[--sz];

    int i = 0;
    while (i * 2 + 1 < sz)
    {
        int a = i * 2 + 1, b = i * 2 + 2;
        if (b < sz&&heap[b] < heap[a])a = b;

        if (heap[a] >= x)break;

        heap[i] = heap[a];
        i = a;
    }

    heap[i] = x;

    return ret;
}

int main()
{
    priority_queue<int> pque;

    pque.push(3);
    pque.push(5);
    pque.push(1);

    while (!pque.empty())
    {
        cout << pque.top() << endl;
        pque.pop();
    }

    system("pause");
    return 0;
}