[haoi2011]防线修建

动态加点维护凸包。

论STL的熟练运用。

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
#include<iostream>
#include<string>
#include<map>
#include<set>
#include<cstdlib>
#include<cmath>
#include<iomanip>
using namespace std;
#define LL long long
#define FILE "dealing"
#define eps 1e-10
#define db double
#define up(i,j,n) for(int i=j;i<=n;i++)
int read(){
	int x=0,f=1,ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+ch-'0',ch=getchar();
	return x*f;
}
const int maxn=101000,mod=1000000007,inf=10000000000000LL;
bool cmin(int& a,int b){return a>b?a=b,true:false;}
bool cmax(int& a,int b){return a<b?a=b,true:false;}
int n,m;
db s,t;
int ch[maxn],p[maxn],b[maxn],q;
int dcmp(db a){if(fabs(a)<eps)return 0;return a<0?-1:1;}
struct vec{
	db x,y,l,r;
	vec(db x=0,db y=0,db l=0,db r=0):x(x),y(y),l(l),r(r){}
}a[maxn];
bool operator<(vec a,vec b){return dcmp(a.x-b.x)<0||(!dcmp(a.x-b.x)&&a.y<b.y);}
bool operator==(vec a,vec b){return !dcmp(a.x-b.x)&&!dcmp(a.y-b.y);}
vec operator+(vec b,vec a){return vec(b.x+a.x,b.y+a.y);}
vec operator-(vec b,vec a){return vec(b.x-a.x,b.y-a.y);}
set<vec> d;
set<vec>::iterator it,pre,rev;
db qik(vec a,vec b){return (b.y-a.y)/(b.x-a.x);}
db dot(vec a,vec b){return a.x*b.x+a.y*b.y;}
db len(vec a){return sqrt(dot(a,a));}
db ans=0;
db y[maxn];
void insert(vec a){
	d.insert(a);
	it=d.find(a);
	pre=--it;it++;
	rev=++it;it--;
	db k=qik(*pre,*rev);
	db b=pre->y-pre->x*k;
	db y=k*a.x+b;
	if(dcmp(y-a.y)>0){d.erase(it);return;}
	ans-=(rev->l);
	while(dcmp(len(*rev-vec(n,0)))){
		//printf("%.2lf %.2lf %.2lf %.2lf
",it->x,it->y,it->l,it->r);
		vec b=*rev,c=*(++rev);
		if(dcmp(qik(a,b)-qik(b,c))<0){
			rev--;
			ans-=rev->r;
			d.erase(rev);
			rev=++it;it--;
		}
		else break;
	}
	while(dcmp(len(*pre-vec(0,0)))){
		vec b=*pre,c=*(--pre);
		if(dcmp(qik(c,b)-qik(b,a))<0){
			pre++;
			ans-=pre->l;
			d.erase(pre);
			pre=--it;it++;
		}
		else break;
	}
	it=d.find(a);
	pre=--it;it++;
	rev=++it;it--;
	vec w=*it,qian=*pre,hou=*rev;
	ans+=(qian.r=w.l=len(*it-*pre));
	ans+=(hou.l=w.r=len(*rev-*it));
	d.erase(it);
	d.erase(pre);
	d.erase(rev);
	d.insert(w);
	d.insert(qian);d.insert(hou);
	it=d.begin();
	//for(;it!=d.end();it++)printf("%.2lf %.2lf %.2lf %.2lf
",it->x,it->y,it->l,it->r);
	//cout<<endl;
	//cout<<ans<<endl;
}
void init(){
	n=read(),s=read(),t=read();
	m=read();ans=n;
	up(i,1,m)a[i].x=read(),a[i].y=read();
	q=read();
	up(i,1,q){
		ch[i]=read();
		if(ch[i]==1)p[i]=read(),b[p[i]]=1;
	}
	d.insert(vec(0,0,0,n));
	d.insert(vec(n,0,n,0));
	insert(vec(s,t));
	up(i,1,m)if(!b[i])insert(a[i]);
	for(int i=q;i>=1;i--){
		if(ch[i]==1)insert(a[p[i]]);
		else y[i]=ans;
	}
	up(i,1,q)if(ch[i]==2)printf("%.2lf
",y[i]);
}
int main(){
	//freopen(FILE".in","r",stdin);
	//freopen(FILE".out","w",stdout);
	init();
	return 0;
}