SW练习_POJ1912_CCW_点线关系_未AC

在CCW的基础上需要优化

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.*;
 
public class Main{
    static Point1912[] data;
    static Point1912 baseP;//起点，也就是最左下侧的点，可以根据坐标的最小值在数据输入的时候找出来
	static int MAX=2087654321;//为了求起点用的
    static int N;
    
    public static void main(String[] args) throws Exception{
        //System.setIn(new FileInputStream(new File("C:\\Users\\XAGDC\\Desktop\\dwarfs-i&o\\dwarfs\\dwarfs.in8")));
            BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
            StringTokenizer st=new StringTokenizer(reader.readLine());
            N=Integer.parseInt(st.nextToken());//房屋的个数
            data=new Point1912[N];
            double startx=MAX;
            double starty=MAX;
            int index=0;
            for (int i = 0; i <N ; i++) {//接收一下房屋的坐标，有负数和小数
                st=new StringTokenizer(reader.readLine());
                double x=Double.parseDouble(st.nextToken());
                double y=Double.parseDouble(st.nextToken());
                data[i]=new Point1912(x,y);
                if(y<starty){//按照y最小来进行
                    starty=y;
                    startx=x;
                    index=i;
                }else if(y==starty){
                    if(x<startx){
                        startx=x;
                        starty=y;
                        index=i;
                    }
                }
            }
        baseP=new Point1912(startx,starty);//这是最左下侧的点，是一个极点
        data[index]=data[0];//将最小的点和当前0位置的点交换下，这样就不用排序了
        data[0]=baseP;
 
        Arrays.sort(data,1,N,new Comparator<Point1912>(){//从baseP开始，将点按照夹角排序
            @Override
            public int compare(Point1912 o1, Point1912 o2) {
                return CCW(baseP,o1,o2) >0 ? -1:1;
            }
        });
		//点在左侧(CCW<0)，V++，   点在右侧，需要回溯V--
        int V=1;
        Point1912[] res=new Point1912[N+2];
        res[0]=data[N-1];
        res[1]=baseP;
        for (int i = 2; i <N ; i++) {
            while(CCW(res[V-1] ,res[V] ,data[i]) <0){
                V--;
            }
            res[++V]=data[i];
        }
        res[++V]=baseP;
            //while( (String str=reader.readLine()).length()>0){
            while( (st=new StringTokenizer(reader.readLine())).hasMoreTokens()){
                Point1912 startP=new Point1912(Double.parseDouble(st.nextToken()),Double.parseDouble(st.nextToken()));
                Point1912 endP=new Point1912(Double.parseDouble(st.nextToken()),Double.parseDouble(st.nextToken()));
                checkCross(res,V,startP,endP);
            }
            reader.close();
        }
        public static void checkCross(Point1912[] res,int V,Point1912 startP,Point1912 endP){
            int tmp=CCW(startP,endP,res[0]);
            boolean cross=false;
            for (int i = 1; i <=V ; i++) {
                int tmp2=CCW(startP,endP,res[i]);
                if(tmp * tmp2 <0){
                    cross=true;
                    break;
                }
            }
            if(cross){
                System.out.println("BAD");
            }else{
                System.out.println("GOOD");
            }
        }
        public static int CCW(Point1912 A,Point1912 B,Point1912 C){
            return A.x*B.y+B.x*C.y+C.x*A.y-(A.y*B.x+B.y*C.x+C.y*A.x) >0?1:-1;
        }
}
class Point1912{
    double x;
    double y;
    public Point1912(double x, double y) {
        this.x = x;
        this.y = y;
    }
    @Override
    public String toString() {
        return "{" + x +
                ", " + y +
                '}';
    }
}