839. 模拟堆

Posted 2021-06-14 幽殇默

https://www.acwing.com/problem/content/841/

#include<cstdio>
#include<iostream>
#include<string>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=1e5+10;
int h[N],ph[N],hp[N],cnt;

void heap_swap(int a,int b)
{
	swap(ph[hp[a]],ph[hp[b]]);
	swap(hp[a],hp[b]);
	swap(h[a],h[b]);
}

void down(int u)
{
	int t=u;
	if(u*2<=cnt&&h[u*2]<h[t]) t=u*2;
	if(u*2+1<=cnt&&h[u*2+1]<h[t]) t=u*2+1;
	if(u!=t)
	{
		heap_swap(u,t);
		down(t);
	}
}

void up(int u)
{
	while(u/2&&h[u]<h[u/2])//如果说有父亲,且我的值小于父结点
	{
		heap_swap(u,u/2);
		u=u>>1;//就往上走
	}
}
int main(void)
{
	int n,m=0;
	scanf("%d",&n);
	while(n--)
	{
		char op[10];
		int k,x;
		scanf("%s",op);
		if(!strcmp(op,"I"))
		{
			scanf("%d",&x);
			cnt++;
			m++;
			ph[m]=cnt,hp[cnt]=m;
			h[cnt]=x;
			up(cnt);
		}
		else if(!strcmp(op,"PM")) printf("%d\\n",h[1]);
		else if(!strcmp(op,"DM"))
		{
			heap_swap(1,cnt);
			cnt--;
			down(1);
		}
		else if(!strcmp(op,"D"))
		{
			scanf("%d",&k);
			k=ph[k];
			heap_swap(k,cnt);
			cnt--;
			up(k);
			down(k);
		}
		else 
		{
			scanf("%d%d",&k,&x);
			k=ph[k];
			h[k]=x;
			up(k);
			down(k);
		}
	}
	return 0;
}