堆【模版】

洛谷（p3378）

這裡以小根堆為例

插入一個元素

void insert(int x)
{
	heap[++siz] = x;
	int pos = siz;
	while(pos != 1)
	{
		if(heap[pos] >= heap[pos/2])break;
		swap(heap[pos],heap[pos/2]);
		pos /= 2;
	}
	return ;
}

刪除堆頂元素

int del()
{
	heap[1] = heap[siz];
	siz --;
	int pos = 1;
	while(pos * 2 <=
 
 siz)
	{
		int to = pos * 2;
		if((pos*2+1<=siz) && (heap[pos*2+1] <heap[pos*2]))
			to = pos * 2 + 1;
		if(heap[pos] > heap[to])swap(heap[pos],heap[to]);
			else break;
		pos = to;
	}
	return 0;
}

綜合起來的程式碼如下

#include<iostream>
#include<cstdio>

using namespace std;

int
 
 heap[1000005],k,z,n,siz;

void insert(int x)
{
    heap[++siz] = x;
    int pos = siz;
    while(pos != 1)
    {
        if(heap[pos] >= heap[pos/2])break;
        swap(heap[pos],heap[pos/2]);
        pos /= 2;
    }
    return ;
}

int del()
{
    heap[1] = heap[siz];
    siz --;
    int pos = 1;
    while
 
(pos * 2 <= siz)
    {
        int to = pos * 2;
        if((pos*2+1<=siz) && (heap[pos*2+1] <heap[pos*2]))
            to = pos * 2 + 1;
        if(heap[pos] > heap[to])swap(heap[pos],heap[to]);
            else break;
        pos = to;
    }
    return 0;
}

int main()
{
    scanf("%d",&n);
    while(n --)
    {
        scanf("%d",&k);
        if(k == 1)
        {
            scanf("%d",&z);
            insert(z);
        }
        if(k == 2)
        {
            printf("%d\n",heap[1]);
        }
        if(k == 3)
        {
            del();
        }
    }
    return 0;
}

P.S. 如果你覺得這個太難看不懂，這有簡單的——優先佇列