矩形面积并 (hdu1542)

来源：互联网发布：nginx负载均衡原理图编辑：程序博客网时间：2024/05/24 01:47
#include <iostream>#include<string>#include<cstdio>#include<cmath>#include<algorithm>using namespace std;const int mmax = 210;const double eps = 1e-8;int sgn(double x){    if(fabs(x)<eps)        return 0;    return x<0?-1:1;}struct Rect{    double x1,x2;    double y1,y2;    void read()    {        scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2);        if(x1>x2)            swap(x1,x2);        if(y1>y2)            swap(y1,y2);    }}R[110];struct node{    int l,r;    int cov;    double len;    int mid()    {        return (l+r)>>1;    }}T[4*mmax];struct Num{    double x;    int id;    bool operator < (const Num &a) const    {        return x<a.x;    }}X[mmax];struct Line{    int l,r;    double y;    int fg;    bool operator < (const Line &a) const    {        return y<a.y;    }}L[mmax];void build(int id,int l,int r){    T[id].l=l,T[id].r=r;    T[id].cov=0,T[id].len=0;    if(l==r)        return ;    int mid=T[id].mid();    build(id<<1,l,mid);    build(id<<1|1,mid+1,r);}double pos[mmax];void updata(int id,int l,int r,int fg){    if(l<=T[id].l && T[id].r<=r)    {        T[id].cov+=fg;        if(T[id].cov)            T[id].len=pos[T[id].r+1]-pos[T[id].l];        else        {            if(T[id].l==T[id].r)                T[id].len=0;            else                T[id].len=T[id<<1].len+T[id<<1|1].len;        }        return ;    }    int mid=T[id].mid();    if(mid>=l)        updata(id<<1,l,r,fg);    if(mid<r)        updata(id<<1|1,l,r,fg);    if(T[id].cov==0)    {        T[id].len=T[id<<1].len+T[id<<1|1].len;    }}int id[mmax];int main(){    int n,ca=0;    while(~scanf("%d",&n)&&n)    {        int cnt=0;        for(int i=0;i<n;i++)        {            R[i].read();            X[cnt].x=R[i].x1;            X[cnt].id=cnt;            cnt++;            X[cnt].x=R[i].x2;            X[cnt].id=cnt;            cnt++;        }        sort(X,X+cnt);        id[0]=1;        pos[1]=X[0].x;        for(int i=1;i<cnt;i++)        {            if(sgn(X[i].x-X[i-1].x)==0)                id[X[i].id]=id[X[i-1].id];            else                id[X[i].id]=id[X[i-1].id]+1;            pos[id[X[i].id]]=X[i].x;        }        for(int i=0;i<n;i++)        {            L[i].l=id[2*i];            L[i].r=id[2*i+1];            L[i].y=R[i].y1;            L[i].fg=1;            L[i+n].l=id[2*i];            L[i+n].r=id[2*i+1];            L[i+n].y=R[i].y2;            L[i+n].fg=-1;        }        sort(L,L+2*n);        build(1,1,id[X[cnt-1].id]-1);        updata(1,L[0].l,L[0].r-1,L[0].fg);        double ans=0.0;        for(int i=1;i<2*n;i++)        {            ans+=(L[i].y-L[i-1].y)*T[1].len;            updata(1,L[i].l,L[i].r-1,L[i].fg);        }        printf("Test case #%d\nTotal explored area: %.2lf\n\n",++ca,ans);    }    return 0;}
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