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artemkorsakov's solution

to Darts in the Java Track

Published at Feb 01 2019 · 0 comments
Test suite


This exercise has changed since this solution was written.

..# Darts

Write a function that returns the earned points in a single toss of a Darts game.

Darts is a game where players throw darts to a target.

In our particular instance of the game, the target rewards with 4 different amounts of points, depending on where the dart lands:

  • If the dart lands outside the target, player earns no points (0 points).
  • If the dart lands in the outer circle of the target, player earns 1 point.
  • If the dart lands in the middle circle of the target, player earns 5 points.
  • If the dart lands in the inner circle of the target, player earns 10 points.

The outer circle has a radius of 10 units (This is equivalent to the total radius for the entire target), the middle circle a radius of 5 units, and the inner circle a radius of 1. Of course, they are all centered to the same point (That is, the circles are concentric) defined by the coordinates (0, 0).

Write a function that given a point in the target (defined by its real cartesian coordinates x and y), returns the correct amount earned by a dart landing in that point.

Running the tests

You can run all the tests for an exercise by entering

$ gradle test

in your terminal.


Inspired by an excersie created by a professor Della Paolera in Argentina

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.


import org.junit.Ignore;
import org.junit.Test;

import static org.junit.Assert.assertEquals;

public class DartsTest {

    public void testDartOutsideTarget() {
        Darts darts = new Darts(15.3, 13.2);
        assertEquals(0, darts.score());

    @Ignore("Remove to run test")
    public void testDartLandsOnBorderOfTarget() {
        Darts darts = new Darts(10, 0);
        assertEquals(1, darts.score());

    @Ignore("Remove to run test")
    public void testDartLandsOnMiddleOfCircle() {
        Darts darts = new Darts(3, 3.7);
        assertEquals(5, darts.score());

    @Ignore("Remove to run test")
    public void testDartLandsOnBorderBetweenOutsideAndMiddleCircles() {
        Darts darts = new Darts(0, 5);
        assertEquals(5, darts.score());

    @Ignore("Remove to run test")
    public void testDartLandsInTheInnerCircle() {
        Darts darts = new Darts(0, 0);
        assertEquals(10, darts.score());

class Darts {
    private int score;

    Darts(double x, double y) {
        double radius = Math.sqrt(x*x + y*y);
        score = radius > 10 ? 0 : radius > 5 ? 1 : radius > 1 ? 5 : 10;

    int score() {
        return score;


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