add grains (#97)

* add `grains`

* Fix missng double quotes

Author: BNAndras

config.json

@@ -98,6 +98,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "grains",
+        "name": "Grains",
+        "uuid": "b960441a-2cd9-4384-bfcc-58a1723873da",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "hamming",
         "name": "Hamming",

exercises/practice/grains/.busted

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

exercises/practice/grains/.docs/instructions.md

@@ -0,0 +1,11 @@
+# Instructions
+
+Calculate the number of grains of wheat on a chessboard.
+
+A chessboard has 64 squares.
+Square 1 has one grain, square 2 has two grains, square 3 has four grains, and so on, doubling each time.
+
+Write code that calculates:
+
+- the number of grains on a given square
+- the total number of grains on the chessboard

exercises/practice/grains/.docs/introduction.md

@@ -0,0 +1,6 @@
+# Introduction
+
+There once was a wise servant who saved the life of a prince.
+The king promised to pay whatever the servant could dream up.
+Knowing that the king loved chess, the servant told the king he would like to have grains of wheat.
+One grain on the first square of a chessboard, with the number of grains doubling on each successive square.

exercises/practice/grains/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "grains.moon"
+    ],
+    "test": [
+      "grains_spec.moon"
+    ],
+    "example": [
+      ".meta/example.moon"
+    ]
+  },
+  "blurb": "Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.",
+  "source": "The CodeRanch Cattle Drive, Assignment 6",
+  "source_url": "https://web.archive.org/web/20240908084142/https://coderanch.com/wiki/718824/Grains"
+}

exercises/practice/grains/.meta/example.moon

@@ -0,0 +1,8 @@
+{
+  square: (n) ->
+    error 'square must be between 1 and 64' unless n >= 1 and n <= 64
+    2 ^ (n - 1)
+
+  total: ->
+    2 ^ 64 - 1
+}

exercises/practice/grains/.meta/spec_generator.moon

@@ -0,0 +1,17 @@
+format = (number) ->
+  string.format '%.0f', number
+
+{
+  module_name: 'Grains'
+
+  generate_test: (case, level) ->
+    lines = {}
+    if type(case.expected) == 'table' and case.expected.error
+      table.insert lines, "assert.has.errors -> Grains.#{case.property} #{case.input.square}, #{quote case.expected.error}"
+    else if case.property == 'square'
+      table.insert lines, "assert.are.equal #{format case.expected}, Grains.#{case.property} #{case.input.square}"
+    else
+      table.insert lines, "assert.are.equal #{format case.expected}, Grains.#{case.property}!"
+
+    table.concat [indent line, level for line in *lines], '\n'
+}

exercises/practice/grains/.meta/tests.toml

@@ -0,0 +1,43 @@
+# 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.
+
+[9fbde8de-36b2-49de-baf2-cd42d6f28405]
+description = "returns the number of grains on the square -> grains on square 1"
+
+[ee1f30c2-01d8-4298-b25d-c677331b5e6d]
+description = "returns the number of grains on the square -> grains on square 2"
+
+[10f45584-2fc3-4875-8ec6-666065d1163b]
+description = "returns the number of grains on the square -> grains on square 3"
+
+[a7cbe01b-36f4-4601-b053-c5f6ae055170]
+description = "returns the number of grains on the square -> grains on square 4"
+
+[c50acc89-8535-44e4-918f-b848ad2817d4]
+description = "returns the number of grains on the square -> grains on square 16"
+
+[acd81b46-c2ad-4951-b848-80d15ed5a04f]
+description = "returns the number of grains on the square -> grains on square 32"
+
+[c73b470a-5efb-4d53-9ac6-c5f6487f227b]
+description = "returns the number of grains on the square -> grains on square 64"
+
+[1d47d832-3e85-4974-9466-5bd35af484e3]
+description = "returns the number of grains on the square -> square 0 is invalid"
+
+[61974483-eeb2-465e-be54-ca5dde366453]
+description = "returns the number of grains on the square -> negative square is invalid"
+
+[a95e4374-f32c-45a7-a10d-ffec475c012f]
+description = "returns the number of grains on the square -> square greater than 64 is invalid"
+
+[6eb07385-3659-4b45-a6be-9dc474222750]
+description = "returns the total number of grains on the board"

exercises/practice/grains/grains.moon

@@ -0,0 +1,7 @@
+{
+  square: (n) ->
+    error 'Implement me!'
+
+  total: ->
+    error 'Implement me!'
+}

exercises/practice/grains/grains_spec.moon

@@ -0,0 +1,36 @@
+Grains = require 'grains'
+
+describe 'grains', ->
+  describe 'returns the number of grains on the square', ->
+    it 'grains on square 1', ->
+      assert.are.equal 1, Grains.square 1
+
+    pending 'grains on square 2', ->
+      assert.are.equal 2, Grains.square 2
+
+    pending 'grains on square 3', ->
+      assert.are.equal 4, Grains.square 3
+
+    pending 'grains on square 4', ->
+      assert.are.equal 8, Grains.square 4
+
+    pending 'grains on square 16', ->
+      assert.are.equal 32768, Grains.square 16
+
+    pending 'grains on square 32', ->
+      assert.are.equal 2147483648, Grains.square 32
+
+    pending 'grains on square 64', ->
+      assert.are.equal 9223372036854775808, Grains.square 64
+
+    pending 'square 0 is invalid', ->
+      assert.has.errors -> Grains.square 0, 'square must be between 1 and 64'
+
+    pending 'negative square is invalid', ->
+      assert.has.errors -> Grains.square -1, 'square must be between 1 and 64'
+
+    pending 'square greater than 64 is invalid', ->
+      assert.has.errors -> Grains.square 65, 'square must be between 1 and 64'
+
+  pending 'returns the total number of grains on the board', ->
+    assert.are.equal 18446744073709551616, Grains.total!