Java Exercises: Check if a point (x, y) is in a triangle or not

Java Basic: Exercise-219 with Solution

Write a Java program to check if a point (x, y) is in a triangle or not. There is a triangle formed by three points.

Input:
x1,y1,x2,y2,x3,y3,xp,yp separated by a single space.

Sample Solution:

Java Code:

import java.util.*;
public class Main { 
    private double outer_product(double x, double y, double x1, double y1, double x2, double y2){
        x1 = x1 - x;
        y1 = y1 - y;
        x2 = x2 - x;
        y2 = y2 - y;
        double s = x1 * y2 - y1 * x2;
        return s;
    } 
    public void point(){
        Scanner sc = new Scanner(System.in);
            double [] x = new double[3];
            double [] y = new double[3];
			System.out.println("Input (x1, y1)");            
                x[0] = sc.nextDouble();
                y[0] = sc.nextDouble();
			System.out.println("Input (x2, y2)");            
                x[1] = sc.nextDouble();
                y[1] = sc.nextDouble();
			System.out.println("Input (x3, y3)");            
                x[2] = sc.nextDouble();
                y[2] = sc.nextDouble();
			System.out.println("Input (xp, yp)");            
                           
            double xp = sc.nextDouble();
            double yp = sc.nextDouble();
            boolean [] ans = new boolean[3];
            for(int i=0; i < 3; i++){
                ans[i] = outer_product(xp, yp, x[i], y[i], x[(i+1)%3], y[(i+1)%3]) > 0.0;
            }
            if(ans[0] == ans[1] && ans[1] == ans[2]){
                
            }
            else{
                System.out.println("The point is outside the triangle.");
            }
      }
    public static void main(String[] args) {
        Main obj = new Main();
        obj.point();
    }
}

Sample Output:

Input (x1, y1)
2
6
Input (x2, y2)
3
5
Input (x3, y3)
4
6
Input (xp, yp)
5
6
The point is outside the triangle.

Flowchart:

Java Code Editor:

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