POJ - 2007 极角排序(Java 实现)

POJ 2007

将所有的点按逆时针输出

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 final int N = 10005;
	static final int inf = 0x3f3f3f3f;
	static final double eps = 1e-6;
	static Point a[] = new Point[N];

	public static void main(String[] args) {
		Scanner cin = new Scanner(new InputStreamReader(System.in));
		int n = 0;
		while (cin.hasNext()) {
			if (a[n] == null)
				a[n] = new Point();
			a[n].x = cin.nextDouble();
			a[n].y = cin.nextDouble();
			n++;
		}
		Arrays.sort(a, 1, n);
		for (int i = 0; i < n; i++) {
			System.out.printf("(%.0f,%.0f)\n", a[i].x, a[i].y);
		}
		cin.close();
	}
}