Add darts exercise (#410)

config.json

@@ -98,6 +98,14 @@
           "searching"
         ]
       },
+      {
+        "slug": "darts",
+        "name": "Darts",
+        "uuid": "6931fb54-5298-48e7-9729-b04c316069a0",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "matrix",
         "name": "Matrix",

exercises/practice/darts/.busted

@@ -0,0 +1,5 @@
+return {
+  default = {
+    ROOT = { '.' }
+  }
+}

exercises/practice/darts/.docs/instructions.md

@@ -0,0 +1,31 @@
+# Instructions
+
+Write a function that returns the earned points in a single toss of a Darts game.
+
+[Darts][darts] is a game where players throw darts at a [target][darts-target].
+
+In our particular instance of the game, the target rewards 4 different amounts of points, depending on where the dart lands:
+
+![Our dart scoreboard with values from a complete miss to a bullseye](https://assets.exercism.org/images/exercises/darts/darts-scoreboard.svg)
+
+- 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 at 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 [Cartesian coordinates][cartesian-coordinates] `x` and `y`, where `x` and `y` are [real][real-numbers]), returns the correct amount earned by a dart landing at that point.
+
+## Credit
+
+The scoreboard image was created by [habere-et-dispertire][habere-et-dispertire] using [Inkscape][inkscape].
+
+[darts]: https://en.wikipedia.org/wiki/Darts
+[darts-target]: https://en.wikipedia.org/wiki/Darts#/media/File:Darts_in_a_dartboard.jpg
+[concentric]: https://mathworld.wolfram.com/ConcentricCircles.html
+[cartesian-coordinates]: https://www.mathsisfun.com/data/cartesian-coordinates.html
+[real-numbers]: https://www.mathsisfun.com/numbers/real-numbers.html
+[habere-et-dispertire]: https://exercism.org/profiles/habere-et-dispertire
+[inkscape]: https://en.wikipedia.org/wiki/Inkscape

exercises/practice/darts/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "darts.lua"
+    ],
+    "test": [
+      "darts_spec.lua"
+    ],
+    "example": [
+      ".meta/example.lua"
+    ]
+  },
+  "blurb": "Write a function that returns the earned points in a single toss of a Darts game.",
+  "source": "Inspired by an exercise created by a professor Della Paolera in Argentina"
+}

exercises/practice/darts/.meta/example.lua

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+local Darts = {}
+
+function Darts.score(x, y)
+  local distance = math.sqrt(x ^ 2 + y ^ 2)
+  if distance <= 1 then
+    return 10
+  elseif distance <= 5 then
+    return 5
+  elseif distance <= 10 then
+    return 1
+  else
+    return 0
+  end
+end
+
+return Darts

exercises/practice/darts/.meta/tests.toml

@@ -0,0 +1,49 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[9033f731-0a3a-4d9c-b1c0-34a1c8362afb]
+description = "Missed target"
+
+[4c9f6ff4-c489-45fd-be8a-1fcb08b4d0ba]
+description = "On the outer circle"
+
+[14378687-ee58-4c9b-a323-b089d5274be8]
+description = "On the middle circle"
+
+[849e2e63-85bd-4fed-bc3b-781ae962e2c9]
+description = "On the inner circle"
+
+[1c5ffd9f-ea66-462f-9f06-a1303de5a226]
+description = "Exactly on center"
+
+[b65abce3-a679-4550-8115-4b74bda06088]
+description = "Near the center"
+
+[66c29c1d-44f5-40cf-9927-e09a1305b399]
+description = "Just within the inner circle"
+
+[d1012f63-c97c-4394-b944-7beb3d0b141a]
+description = "Just outside the inner circle"
+
+[ab2b5666-b0b4-49c3-9b27-205e790ed945]
+description = "Just within the middle circle"
+
+[70f1424e-d690-4860-8caf-9740a52c0161]
+description = "Just outside the middle circle"
+
+[a7dbf8db-419c-4712-8a7f-67602b69b293]
+description = "Just within the outer circle"
+
+[e0f39315-9f9a-4546-96e4-a9475b885aa7]
+description = "Just outside the outer circle"
+
+[045d7d18-d863-4229-818e-b50828c75d19]
+description = "Asymmetric position between the inner and middle circles"

exercises/practice/darts/darts.lua

@@ -0,0 +1,7 @@
+local Darts = {}
+
+function Darts.score(x, y)
+
+end
+
+return Darts

exercises/practice/darts/darts_spec.lua

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+local Darts = require 'darts'
+
+describe('darts', function()
+  it('Missed target', function()
+    assert.equal(0, Darts.score(-9, 9))
+  end)
+
+  it('On the outer circle', function()
+    assert.equal(1, Darts.score(0, 10))
+  end)
+
+  it('On the middle circle', function()
+    assert.equal(5, Darts.score(-5, 0))
+  end)
+
+  it('On the inner circle', function()
+    assert.equal(10, Darts.score(0, -1))
+  end)
+
+  it('Exactly on center', function()
+    assert.equal(10, Darts.score(0, 0))
+  end)
+
+  it('Near the center', function()
+    assert.equal(10, Darts.score(-0.1, -0.1))
+  end)
+
+  it('Just within the inner circle', function()
+    assert.equal(10, Darts.score(0.7, 0.7))
+  end)
+
+  it('Just outside the inner circle', function()
+    assert.equal(5, Darts.score(0.8, -0.8))
+  end)
+
+  it('Just within the middle circle', function()
+    assert.equal(5, Darts.score(-3.5, 3.5))
+  end)
+
+  it('Just outside the middle circle', function()
+    assert.equal(1, Darts.score(-3.6, -3.6))
+  end)
+
+  it('Just within the outer circle', function()
+    assert.equal(1, Darts.score(-7.0, 7.0))
+  end)
+
+  it('Just outside the outer circle', function()
+    assert.equal(0, Darts.score(7.1, -7.1))
+  end)
+
+  it('Asymmetric position between the inner and middle circles', function()
+    assert.equal(5, Darts.score(0.5, -4))
+  end)
+end)