Gym-101915B Ali and Wi-Fi 计算几何 求两圆交点

题面

题意:给你n个圆,每个圆有一个权值,你可以选择一个点,可以获得覆盖这个点的圆中,权值最大的m个的权值,问最多权值是多少

题解:好像是叙利亚的题....我们画画图就知道,我们要找的就是圆与圆交的那部分里面的点,我们再仔细看看,

2个圆的交点一定在啊！

别急啊,两个圆包含了,都是交点,取哪呢？当然小圆圆心就够了啊(圆又不多,写的时候直接把所有的圆心都丢进去了)

然后枚举判断每个点有没有被在m个圆中就行了,这里维护最大的m个,用个堆就好了

 #include<bits/stdc++.h>
 using namespace std;
 typedef long double ld;
 const ld eps = 1e-;
 int dcmp(ld x)
 {
     if(fabs(x) < eps) return ;
     return x <  ? - : ;
 }
 ld sqr(ld x) { return x * x; }
 struct Point
 {
     ld x, y;
     Point(ld x = , ld y = ):x(x), y(y) {}
 };
 Point operator - (const Point& A, const Point& B)
 {
     return Point(A.x - B.x, A.y - B.y);
 }
 bool operator == (const Point& A, const Point& B)
 {
     return dcmp(A.x - B.x) ==  && dcmp(A.y - B.x) == ;
 }
 ld Dot(const Point& A, const Point& B)
 {
     return A.x * B.x + A.y * B.y;
 }
 ld dis(Point a,Point b)
 {
     return sqrt(sqr(a.x-b.x)+sqr(a.y-b.y));
 }
 ld Length(const Point& A) { return sqrt(Dot(A, A)); }
 ld angle(Point v) { return atan2(v.y, v.x); }
 struct Circle
 {
     Point c;
     ld r,v;
     Circle() {}
     Circle(Point c, ld r):c(c), r(r) {}
     inline Point point(double a)
     {
         return Point(c.x+cos(a)*r, c.y+sin(a)*r);
     }
 }a[];
 int getCircleCircleIntersection(Circle C1, Circle C2,Point &t1,Point &t2)
 {
     ld d = Length(C1.c - C2.c);
     if(dcmp(d) == )
     {
         if(dcmp(C1.r - C2.r) == ) return -;
         return ;
     }
     if(dcmp(C1.r + C2.r - d) < ) return ;
     if(dcmp(fabs(C1.r-C2.r) - d) > ) return ;
     ld a = angle(C2.c - C1.c);
     ld da = acos((C1.r*C1.r + d*d - C2.r*C2.r) / (*C1.r*d));
     Point p1 = C1.point(a-da), p2 = C1.point(a+da);
     t1=p1;
     if(p1 == p2) return ;
     t2=p2;
     return ;
 }
 Point jd[];
 ld ans,sum;
 int n,m,T,tot;
 priority_queue<int,vector<int>,greater<int> >q;
 int main()
 {
     scanf("%d",&T);
     while (T--)
     {
         tot=;
         ans=;
         scanf("%d%d",&n,&m);
         for (int i=;i<=n;i++) scanf("%Lf%Lf%Lf%Lf",&a[i].c.x,&a[i].c.y,&a[i].r,&a[i].v);
         for (int i=;i<=n;i++)
             for (int j=i+;j<=n;j++)
             {
                 Point t1,t2;
                 int why=getCircleCircleIntersection(a[i],a[j],t1,t2);
                 if (why==)
                 {
                     tot++;
                     jd[tot]=t1;
                 }else
                 if (why==)
                 {
                     tot++;jd[tot]=t1;
                     tot++;jd[tot]=t2;
                 }
             }
         for (int i=;i<=n;i++)
         {
             tot++;
             jd[tot]=a[i].c;
         }
         for (int i=;i<=tot;i++)
         {
             for (int j=;j<=n;j++)
                 if (dcmp(dis(jd[i],a[j].c)-a[j].r)<=)
                 {
                     q.push(a[j].v);
                     if ((int)q.size()>m) q.pop();
                 }
             sum=;
             while (!q.empty()) sum+=q.top(),q.pop();
             ans=max(ans,sum);
         }
         printf("%.Lf\n",ans);
     }
 }