7-8 编程练习题答案

import java.util.Scanner;

public class Test
{
	public static void main(String[] args)
	{
		Scanner input = new Scanner(System.in);
		System.out.print("Enter the number of points: ");
		int numberOfPoints = input.nextInt();

		double[][] points = new double[numberOfPoints][2];
		System.out.print("Enter " + numberOfPoints + " points: ");
		for(int i = 0; i < points.length; i++)
		{
			points[i][0] = input.nextDouble();
			points[i][1] = input.nextDouble();
		}

		int p1 = 0, p2 = 1;
		double shortestDistance = distance(points[p1][0], points[p1][1], points[p2][0], points[p2][1]);

		double[][][] equalDistance = new double[numberOfPoints][2][2];

		for(int i = 0; i < points.length; i++)
		{
			for(int j = i + 1; j < points.length; j++)
			{
				double distance = distance(points[i][0], points[i][1], points[j][0], points[j][1]);
				if(shortestDistance > distance)
				{
					p1 = i; 
					p2 = j;
					shortestDistance = distance;
				}
			}
		}

		System.arraycopy(points[p1], 0, equalDistance[0][0], 0, points[p1].length);
		System.arraycopy(points[p2], 0, equalDistance[0][1], 0, points[p2].length);

		int count = 1;
		for(int i = 0; i < points.length; i++)
		{
			for(int j = i + 1; j < points.length; j++)
			{
				double distance = distance(points[i][0], points[i][1], points[j][0], points[j][1]);
				if((shortestDistance == distance) && ((p1 != i) || (p2 != j)))
				{
					System.arraycopy(points[i], 0, equalDistance[count][0], 0, points[i].length);
					System.arraycopy(points[j], 0, equalDistance[count][1], 0, points[j].length);
					count++;
				}
			}
		}

		System.out.println("The equal distance points are: ");
		for(int i = 0; i < equalDistance.length; i++)
		{
			if((equalDistance[i][0][0] == 0) && (equalDistance[i][0][1] == 0) && (equalDistance[i][1][0] == 0) && (equalDistance[i][1][1] == 0) )
				continue;
			else
				System.out.println("(" + equalDistance[i][0][0] + ", " + equalDistance[i][0][1] + ") (" + equalDistance[i][1][0] + ", " + equalDistance[i][1][1] + ")");
		}
	}

	public static double distance(double x1, double y1, double x2, double y2)
	{
		return Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
	}
}