Poj Solution 1410

http://poj.org/problem?id=1410

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

public class Main{
 public static void main(String[] args){
  Scanner scanner=new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        int n=scanner.nextInt();
        double dx1,dx2,dy1,dy2;
        double x1,x2,y1,y2;
        double k,b;
        double d1,d2,d3,d4;
        for (int i=0;i<n ;i++ ){
            x1=scanner.nextDouble();
            y1=scanner.nextDouble();
            x2=scanner.nextDouble();
            y2=scanner.nextDouble();
            dx1=scanner.nextDouble();
            dy1=scanner.nextDouble();
            dx2=scanner.nextDouble();
            dy2=scanner.nextDouble();
            if (dx1>dx2){
                double tx=dx1;
                dx1=dx2;
                dx2=tx;
            }
            if (dy1>dy2){
                double ty=dy1;
                dy1=dy2;
                dy2=ty;
            }
            if ((x1< dx1&&x2< dx1)||(x1>dx2&&x2>dx2)){
                System.out.println("F");
            }
            else if ((y1< dy1&&y2< dy1)||(y1>dy2&&y2>dy2)){
                System.out.println("F");
            }
            else{
                if (x1==x2){
                    System.out.println("T");
                }
                else{
            k=(y2-y1)/(x2-x1);
            b=y1-k*x1;
            d1=dy1-k*dx1-b;
            d2=dy2-k*dx2-b;
                 d3=dy1-k*dx2-b;
            d4=dy2-k*dx1-b;
            if ((d1>0&&d2>0&&d3>0&&d4>0)||(d1<0&&d2<0&&d3<0&&d4<0)){
                System.out.println("F");
            }
            else{
                System.out.println("T");
            }
        }
    }
     }
   }
}