POJ 2398 - Toy Storage - [计算几何基础题][同POJ2318]

#include<cstdio>
#include<cstring>
#include<cmath>
#include<vector>
#include<algorithm>
#define MAX 5005
#define M_PI 3.14159265358979323846 //POJ的math头文件好像没有这个定义
using namespace std;

const double eps = 1e-6;

struct Point{
    double x,y;
    Point(double tx=0,double ty=0):x(tx),y(ty){}
};
typedef Point Vctor;

Vctor operator + (Vctor A,Vctor B){return Vctor(A.x+B.x,A.y+B.y);}
Vctor operator - (Point A,Point B){return Vctor(A.x-B.x,A.y-B.y);}
Vctor operator * (Vctor A,double p){return Vctor(A.x*p,A.y*p);}
Vctor operator / (Vctor A,double p){return Vctor(A.x/p,A.y/p);}
bool operator < (Point A,Point B){return A.x < B.x || (A.x == B.x && A.y < B.y);}

struct Line{
    Point p;
    Vctor v;
    Line(Point p=0,Vctor v=Vctor(0,0)):p(p),v(v){}
    Point point(double t){return p + v*t;} //获得直线上的距离p点t个单位长度的点
};

double Cross(Vctor A,Vctor B){return A.x*B.y-A.y*B.x;}

int dcmp(double x)
{
    if(fabs(x)<eps) return 0;
    else return (x<0)?(-1):(1);
}
bool operator == (Point A,Point B){return dcmp(A.x-B.x)==0 && dcmp(A.y-B.y)==0;}

int n,m;
Point upper_left,lower_right;
Line x_axis;//下边界
Line cardboard[MAX];//隔板
Point toy;
int area[MAX],cnt[MAX];//记录每个区域的

int Left_of_Line(Line l,Point p)
{
    if(Cross(l.v,p-l.p)>0) return 1;//左边
    else return 0;
}
int where(Point toy)
{
    int l=0,r=n+1;
    while(r-l>1)
    {
        int mid=(l+r)/2;
        if(Left_of_Line(cardboard[mid],toy)) r=mid;
        else l=mid;
    }
    return l;
}

bool cmp(Line a,Line b)
{
    if(a.p==b.p) return (a.p+a.v)<(b.p+b.v);
    else return a.p<b.p;
}
int main()
{
    while(scanf("%d",&n) && n!=0)
    {
        scanf("%d%lf%lf%lf%lf",&m,&upper_left.x,&upper_left.y,&lower_right.x,&lower_right.y);

        x_axis=Line(lower_right,Vctor(-1,0));
        cardboard[0]=Line(Point(upper_left.x,lower_right.y),Vctor(0,1)), cardboard[n+1]=Line(lower_right,Vctor(0,1));

        Point U=Point(0,upper_left.y),L=Point(0,lower_right.y);
        for(int i=1;i<=n;i++)
        {
            scanf("%lf%lf",&U.x,&L.x);
            cardboard[i]=Line(L,U-L);
        }
        sort(cardboard+1,cardboard+n+1,cmp);

        memset(area,0,sizeof(area));
        for(int i=1;i<=m;i++)
        {
            scanf("%lf%lf",&toy.x,&toy.y);
            area[where(toy)]++;
        }
        memset(cnt,0,sizeof(cnt));
        for(int i=0;i<=n;i++) cnt[area[i]]++;
        printf("Box\n");
        for(int i=1;i<=m;i++)
        {
            if(cnt[i]==0) continue;
            printf("%d: %d\n",i,cnt[i]);
        }
    }
}