zoj1041 Transmitters

//zoj1041 Transmitters

//Accepted 1041 C++ 00:00.00 424K

#include <stdio.h>

#include <math.h>

#define MAXN 1000

struct point {double x,y;}c;

double r;

double xmult(double x1,double y1,double x2,double y2){return x1*y2-x2*y1;}

double dist(point p1,point p2){ return sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));}

void solve()

{

int i,j,n,num,max,cnt;

double dx,dy,dt;

point pt,p[MAXN];

scanf ("%d",&n);

num = 0;

for (i=0; i<n; ++i) {

scanf ("%lf %lf",&pt.x,&pt.y);

if (dist(pt,c)<=r) p[num++] = pt;

}

if (num<=2){

printf ("%d/n",num);

return ;

}

max = 2;

for (i=0; i<num; ++i){

cnt = 1;

dy = p[i].y-c.y;

dx = p[i].x-c.x;

for (j=0; j<num; ++j){

if (i==j) continue;

if (xmult(p[j].x-c.x,p[j].y-c.y,dx,dy)>=0.0) cnt++;

}

if (cnt>max) max = cnt;

}

printf ("%d/n",max);

}

int main()

{

#ifdef ONLINE_JUDGE

#else

freopen("1041.txt","r",stdin);

#endif

while (scanf("%lf %lf %lf",&c.x,&c.y,&r)!=EOF){

if (r<=0.0) break;

solve();

}

#ifdef ONLINE_JUDGE

#else

fclose(stdin);

#endif

return 0;

}