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Monday, 29 August 2016

Chapter 8 Exercise 34, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

8.34 (Geometry: rightmost lowest point) In computational geometry, often you need
to find the rightmost lowest point in a set of points. Write the following method
that returns the rightmost lowest point in a set of points.
public static double[]
getRightmostLowestPoint(double[][] points)
Write a test program that prompts the user to enter the coordinates of six points
and displays the rightmost lowest point. Here is a sample run:
Enter 6 points: 1.5 2.5 -3 4.5 5.6 -7 6.5 -7 8 1 10 2.5
The rightmost lowest point is (6.5, -7.0)


import java.util.Scanner;
public class Exercise_34 {

    static final int X = 0;
    static final int Y = 1;

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);


        double[][] points = new double[6][2];
        System.out.print("Enter 6 points: ");
        for (int i = 0; i < points.length; i++)
            for (int j = 0; j < points[i].length; j++)
                points[i][j] = input.nextDouble();

        double[] point = getRightMostLowestPoint(points);
        double[] point2 = getLeftMostLowestPoint(points);
        System.out.println("The rightmost lowest point is (" + point[0] + ", " + point[1] + ")");
        System.out.println("The leftmost lowest point is (" + point2[0] + ", " + point2[1] + ")");
    }

    public static double[] getLeftMostLowestPoint(double[][] p) {

        double[] leftMost;
        leftMost = p[0];

        for (int i = 1; i < p.length; i++) {
            if (p[i][Y] < leftMost[Y]) {
                leftMost = p[i];
            } else if (p[i][Y] == leftMost[Y] && p[i][X] < leftMost[X]) {
                leftMost = p[i];
            }
        }
        return new double[] {leftMost[X], leftMost[Y]};

    }

    public static double[] getRightMostLowestPoint(double[][] p) {

        double[] rightMost;
        rightMost = p[0];

        for (int i = 1; i < p.length; i++) {

            if (p[i][Y] < rightMost[Y]) {

                rightMost = p[i];
            } else if (p[i][Y] == rightMost[Y] && p[i][X] > rightMost[X]) {

                rightMost = p[i];
            }
        }
        return new double[] {rightMost[X], rightMost[Y]};

    }
}

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