Instructions

Test suite

Solution

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.

To run the tests, run the command `dotnet test`

from within the exercise directory.

Initially, only the first test will be enabled. This is to encourage you to solve the exercise one step at a time.
Once you get the first test passing, remove the `Skip`

property from the next test and work on getting that test passing.
Once none of the tests are skipped and they are all passing, you can submit your solution
using `exercism submit Darts.cs`

For more detailed information about the C# track, including how to get help if you're having trouble, please visit the exercism.io C# language page.

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

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

```
// This file was auto-generated based on version 1.0.0 of the canonical data.
using Xunit;
public class DartsTest
{
[Fact]
public void A_dart_lands_outside_the_target()
{
Assert.Equal(0, Darts.Score(15.3, 13.2));
}
[Fact(Skip = "Remove to run test")]
public void A_dart_lands_just_in_the_border_of_the_target()
{
Assert.Equal(1, Darts.Score(10, 0));
}
[Fact(Skip = "Remove to run test")]
public void A_dart_lands_in_the_middle_circle()
{
Assert.Equal(5, Darts.Score(3, 3.7));
}
[Fact(Skip = "Remove to run test")]
public void A_dart_lands_right_in_the_border_between_outside_and_middle_circles()
{
Assert.Equal(5, Darts.Score(0, 5));
}
[Fact(Skip = "Remove to run test")]
public void A_dart_lands_in_the_inner_circle()
{
Assert.Equal(10, Darts.Score(0, 0));
}
}
```

```
using System;
public static class Darts
{
public static int Score(double x, double y)
{
var radius = Math.Sqrt(x * x + y * y);
return radius - 1 < double.Epsilon ? 10 :
radius - 5 < double.Epsilon ? 5 :
radius - 10 < double.Epsilon ? 1 :
0;
}
}
```

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

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## Community comments

HI! May I ask you, why did you use this

`Math.Sqrt(x * x + y * y)`

/same: sqrt{x²+y²} formula?Hi! I reasoned like this: The point is located in (x, y) coordinates - this means that the radius is the hypotenuse of the triangle with the x, y legs. Then I used (the Pythagorean theorem): x²+y² = radius². I hope that I reasoned correctly.

Is the radius not actually the "legs" x, y up to a certain point (x: -10 / +10) (y: -10 / +10 - for a whole circle)? And hypotenuse the segment between x and y?

And when we talk about triangles (four of them), does that mean we have a square in the end, right? Maybe I do not understand it correctly, but are we not talking about circles?

The task says:

The centre of the circles is the point (0, 0). I think the radius is the distance from the point (0, 0) to the point (x, y). The distance from the point (xa, ya) to the point (xb, yb) equals distance = sqrt{(xb - xa)² + (yb - ya)²} or distance = sqrt{x²+y²}.

I think If the borders are defined by dots (10, 0), (-10, 0), (0, -10), (0, 10) it's a square, not a circle.

I need to draw that in order to understand, but now i got it! Thanks a lot! Большое спасибо!

You are welcome!)