Poj 1106 Transmitters

Poj 1106 Transmitters

import java.io.*;
import java.util.*;

public class Main {
static class Point implements Comparable<Point> {
double x, y;

@Override
public int compareTo(Point a) {
return (int) cross(a);
}

public double cross(Point a) {
return a.x * y - x * a.y;
}
}

static double cross(Point st, Point a, Point b) {
return (a.x - st.x) * (b.y - st.y) - (b.x - st.x) * (a.y - st.y);
}

static double dist(Point a1, Point a2) {
return (a1.x - a2.x) * (a1.x - a2.x) + (a1.y - a2.y) * (a1.y - a2.y);
}

static final int N = 10005;
static final int inf = 0x3f3f3f3f;
static final double eps = 1e-9;
static Point a[] = new Point
;

public static void main(String[] args) {
Scanner cin = new Scanner(new InputStreamReader(System.in));
while (cin.hasNext()) {
Point st = new Point(), tmp = new Point();
st.x = cin.nextDouble();
st.y = cin.nextDouble();
double r = cin.nextDouble();
double d;
int n = cin.nextInt();
int cnt = 0;
for (int i = 0; i < n; i++) {
tmp.x = cin.nextDouble();
tmp.y = cin.nextDouble();
d = dist(st, tmp);
if (d < r * r || Math.abs(d - r * r) < eps) {
cnt++;
if (a[cnt] == null)
a[cnt] = new Point();
a[cnt].x = tmp.x;
a[cnt].y = tmp.y;
}
}
int ans = 0;
for (int i = 1; i <= cnt; i++) {
int count = 1;
for (int j = 1; j <= cnt; j++) {
if (i != j && cross(st, a[i], a[j]) <= 0)
count++;
}
if (count > ans)
ans = count;
}
System.out.println(ans);
}
cin.close();
}
}