[平衡树动态维护凸包] BZOJ 2300 [HAOI2011]防线修建

来源：互联网发布：易语言外网聊天室源码编辑：程序博客网时间：2024/05/17 05:13
就是叉积乱搞 set水过
#include<cstdio>#include<cstdlib>#include<algorithm>#include<iostream>#include<set>#include<cmath>using namespace std; inline char nc(){    static char buf[100000],*p1=buf,*p2=buf;    if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }    return *p1++;} inline void read(int &x){    char c=nc(),b=1;    for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;    for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;} const int N=200005; inline double sqr(int x){ return (double)x*x; } struct Point{    int x,y;    Point(int x=0,int y=0):x(x),y(y) { }    friend istream& operator >> (istream &_,Point &x){ read(x.x); read(x.y); return _; }    friend bool operator < (Point A,Point B){ return A.x==B.x?A.y<B.y:A.x<B.x; }    friend int operator * (Point A,Point B){ return A.x*B.y-A.y*B.x; }    friend Point operator - (Point A,Point B){ return Point(A.x-B.x,A.y-B.y); }    friend double dist(Point A,Point B){ return sqrt(sqr(A.x-B.x)+sqr(A.y-B.y)); }}b[N],a[N];int del[N],tot; set<Point> Set;typedef set<Point>::iterator ITER; int n,m;double Ans,ans[N];int Q,que[N],qtot; inline void Ins(Point x){    ITER r=Set.lower_bound(x),l=r,t;    l--;    if((*r-*l)*(x-*l)<0) return;    Ans-=dist(*l,*r);    Set.insert(x);    while (1)    {        t=r; r++;        if(r==Set.end()) break;        if((*r-x)*(*t-x)>0) break;        Ans-=dist(*t,*r);        Set.erase(t);    }    while (1)    {        if (l==Set.begin()) break;        t=l; l--;        if((*t-x)*(*l-x)>0) break;        Ans-=dist(*t,*l);        Set.erase(t);    }    Set.insert(x);    l=r=Set.find(x);    l--; r++;    Ans+=dist(*l,x)+dist(*r,x);} int main(){    Point tmp; int order,x;    read(m); cin>>tmp;    Set.insert(Point(0,0)); Set.insert(Point(m,0)); Set.insert(tmp);    Ans+=dist(Point(0,0),tmp); Ans+=dist(Point(m,0),tmp);    read(n);    for (int i=1;i<=n;i++) cin>>a[i];    read(Q);    for (int i=1;i<=Q;i++){        read(order);        if (order==1){            read(x); del[x]=1; b[++tot]=a[x];        }else{            que[++qtot]=tot;        }    }    for (int i=1;i<=n;i++) if (!del[i]) Ins(a[i]);    for (int i=qtot;i;i--)    {        while (tot>que[i])            Ins(b[tot--]);        ans[i]=Ans;    }    for (int i=1;i<=qtot;i++)        printf("%.2lf\n",ans[i]);    return 0;}
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