(中心城市）給定一組城市，中心城市是和所有其他城市之間具有最短距離的城市。編寫一個Java程序，提示用戶輸人城市的數目以及城市的位置（座標)，找到中心城市以及和所有其他城市的總距離。

package chapter08;

import java.util.Scanner;

/**
 * @author mazouri
 * @create 2020-03-31 22:00
 */
public class Question21 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the number of cities: ");
        int numberOfCities = scanner.nextInt();
        System.out.print("Enter the coordinates of the cities: ");
        double[][] location = new double[numberOfCities][2];
        //輸入數據
        for (int i = 0; i < location.length; i++) {
            location[i][0] = scanner.nextDouble();
            location[i][1] = scanner.nextDouble();
        }

        double minTotal = totalDistance(location, 0);
        int minIndex = 0;
        for (int i = 0; i < location.length; i++) {
            double total = totalDistance(location, i);

            if (minTotal > total) {
                minTotal = total;
                minIndex = i;
            }
        }
        System.out.println("The central city is at (" +
                location[minIndex][0] + ", " + location[minIndex][1] + ")");
        System.out.println("The total distance to all other cities is " +
                minTotal);
    }

    /**
     * @param location 存放城市的座標
     * @param i        與其他城市計算距離的某一城市位置
     * @return 某一點與其他點的總距離
     */
    public static double totalDistance(double[][] location, int i) {
        double totalDistance = 0;
        for (int j = 0; j < location.length; j++) {

            //二維數據是一維數組的數組
            totalDistance += distance(location[i], location[j]);
        }
        return totalDistance;
    }

    /**
     * @param city1 本次不變的城市
     * @param city2 一直變化的城市
     * @return 與其他城市的長度
     */
    public static double distance(double[] city1, double[] city2) {

        return Math.sqrt((city1[0] - city2[0]) * (city1[0] - city2[0]) +
                (city1[1] - city2[1]) * (city1[1] - city2[1]));
    }
}