luogu P3378 【模板】堆

最新推荐文章于 2024-02-28 22:19:43 发布

转载最新推荐文章于 2024-02-28 22:19:43 发布 · 68 阅读

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原文链接：http://www.cnblogs.com/ZlycerQan/p/6805313.html

本文介绍了一道利用手写堆解决的问题，并通过对比展示了使用标准库优先队列的简洁实现方式。作者首先手动实现了堆的数据结构来处理一系列数值的插入与删除操作，随后又提供了使用C++标准库中的优先队列简化代码的例子。

二次联通门 : luogu P3378 【模板】堆

/*
    一看题
    Woc 竟然还有我没做过的板子题 
    
    于是刷刷刷打了个手写堆
    
    后顺手写上了优先队列..233333 
    
*/
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <queue>

#define Max 6000000

using namespace std;

void read (int &now)
{
    now = 0;
    char word = getchar ();
    bool flag = false;
    while (word < '0' || word > '9')
    {
        if (word == '-')
            flag = true;
        word = getchar ();
    }
    while (word >= '0' && word <= '9')
    {
        now = now * 10 + word - '0';
        word = getchar ();
    }
    if (flag)
        now = -now;
}

int heap [Max]; 
int Count;

void push (int x)
{
    heap [++Count] = x;
    int now = Count;
    while (now > 1)
    {
        int next = now >> 1; 
        if (heap [now] < heap [next])
            swap (heap [now], heap [next]);
        now = next;        
    }
}

int top ()
{
    return heap [1];
}

void pop ()
{
    int now = 1;
    heap [now] = heap [Count--];
    while ((now << 1) <= Count)
    {
        int next = now << 1;
        if ((next | 1) >= Count && heap [next | 1] < heap [next])
            next++;
        if (heap [now] > heap [next])
            swap (heap [now], heap [next]);
        else 
            break;
        now = next;
    }
}

priority_queue <int, vector <int>, greater <int> > Queue;

int main ()
{
    int N;
    read (N);
    int type, x;
    while (N--)
    {
        read (type);
        switch (type)
        {
            case 1:
            {
                read (x);
                Queue.push (x); 
                break;
            }
            case 2:
            {
                printf ("%d\n", Queue.top ()); 
                break;
            }
            default :
            {
                Queue.pop (); 
                break;
            }
        }
    }
    return 0;
}

转载于:https://www.cnblogs.com/ZlycerQan/p/6805313.html