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https://github.com/Kiritow/OJ-Problems-Source.git
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89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
#include<iostream>
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#include<vector>
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#include<math.h>
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using namespace std;
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#define eps 1e-8
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const int maxn=105;
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struct point
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{
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double x,y;
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};
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struct circle
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{
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point p;
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double r;
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}c[maxn];
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vector<point>v;
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double dis(point p1,point p2)
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{
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return sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));
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}
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point intersection(point u1,point u2,point v1,point v2)
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{
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point ret=u1;
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double t=((u1.x-v1.x)*(v1.y-v2.y)-(u1.y-v1.y)*(v1.x-v2.x))/((u1.x-u2.x)*(v1.y-v2.y)-(u1.y-u2.y)*(v1.x-v2.x));
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ret.x+=(u2.x-u1.x)*t;
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ret.y+=(u2.y-u1.y)*t;
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return ret;
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}
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int intersect_circle_circle(point c1,double r1,point c2,double r2)
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{
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return dis(c1,c2)<r1+r2+eps&&dis(c1,c2)>fabs(r1-r2)-eps;
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}
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void intersection_line_circle(point c,double r,point l1,point l2,point &p1,point &p2)
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{
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point p=c;
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double t;
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p.x+=l1.y-l2.y;
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p.y+=l2.x-l1.x;
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p=intersection(p,c,l1,l2);
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t=sqrt(r*r-dis(p,c)*dis(p,c))/dis(l1,l2);
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p1.x=p.x+(l2.x-l1.x)*t;
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p1.y=p.y+(l2.y-l1.y)*t;
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p2.x=p.x-(l2.x-l1.x)*t;
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p2.y=p.x-(l2.y-l1.y)*t;
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}
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void intersection_circle_circle(point c1,double r1,point c2,double r2,point &p1,point &p2)
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{
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point u,v;
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double t;
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t=(1+(r1*r1-r2*r2)/dis(c1,c2)/dis(c1,c2))/2;
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u.x=c1.x+(c2.x-c1.x)*t;
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u.y=c1.y+(c2.y-c1.y)*t;
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v.x=u.x+c1.y-c2.y;
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v.y=u.y-c1.x+c2.x;
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intersection_line_circle(c1,r1,u,v,p1,p2);
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}
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int main()
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{
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int n;
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while(scanf("%d",&n)!=EOF)
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{
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int cnt=0;
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v.clear();
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for(int i=0;i<n;i++)
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{
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cin>>c[i].p.x>>c[i].p.y>>c[i].r;
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v.push_back(c[i].p);
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}
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for(int i=0;i<n;i++)
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for(int j=0;j<i;j++)
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if(intersect_circle_circle(c[i].p,c[i].r,c[j].p,c[j].r))
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{
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point x,y;
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intersection_circle_circle(c[i].p, c[i].r, c[j].p, c[j].r, x, y);
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v.push_back(x);v.push_back(y);
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}
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int maxt=-1;
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for(int i=0;i<v.size();i++)
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{
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int cnt=0;
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for(int j=0;j<n;j++)
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cnt+=dis(v[i],c[j].p)<c[j].r+eps;
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maxt=max(cnt,maxt);
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}
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cout<<maxt<<endl;
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}
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return 0;
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}
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