Training.java

import java.awt.geom.Point2D;
import java.util.Scanner;

public class Training {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int[][] vertexCoordinates = new int[3][2];
        for (int side = 0; side < vertexCoordinates.length; side++) {
            for (int i = 0; i < vertexCoordinates[side].length; i++) {
                vertexCoordinates[side][i] = in.nextInt();
            }
        }

        double[] sideLength = getSideLength(vertexCoordinates);
        double sum = 0;
        for (double aSideLength : sideLength) {
            sum += aSideLength;
        }
        System.out.printf("%.6f", sum);
    }

    public static double[] getSideLength(int[][] vertexCoordinates)
    {
        double[] sideLength = new double[3];
        for (int side = 0; side < sideLength.length; side++) {
            int nextSide = side + 1;
            if (nextSide == 3) {
                nextSide = 0;
            }
            sideLength[side] = Point2D.distance(vertexCoordinates[side][0], vertexCoordinates[side][1], vertexCoordinates[nextSide][0], vertexCoordinates[nextSide][1]);
        }
        return sideLength;
    }

}