Add sum-of-multiples

config.json

@@ -535,6 +535,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "sum-of-multiples",
+        "name": "Sum of Multiples",
+        "uuid": "2e6dcbe2-bef0-4f37-b048-7701fe116c4c",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "triangle",
         "name": "Triangle",

exercises/practice/sum-of-multiples/.docs/instructions.md

@@ -0,0 +1,27 @@
+# Instructions
+
+Your task is to write the code that calculates the energy points that get awarded to players when they complete a level.
+
+The points awarded depend on two things:
+
+- The level (a number) that the player completed.
+- The base value of each magical item collected by the player during that level.
+
+The energy points are awarded according to the following rules:
+
+1. For each magical item, take the base value and find all the multiples of that value that are less than the level number.
+2. Combine the sets of numbers.
+3. Remove any duplicates.
+4. Calculate the sum of all the numbers that are left.
+
+Let's look at an example:
+
+**The player completed level 20 and found two magical items with base values of 3 and 5.**
+
+To calculate the energy points earned by the player, we need to find all the unique multiples of these base values that are less than level 20.
+
+- Multiples of 3 less than 20: `{3, 6, 9, 12, 15, 18}`
+- Multiples of 5 less than 20: `{5, 10, 15}`
+- Combine the sets and remove duplicates: `{3, 5, 6, 9, 10, 12, 15, 18}`
+- Sum the unique multiples: `3 + 5 + 6 + 9 + 10 + 12 + 15 + 18 = 78`
+- Therefore, the player earns **78** energy points for completing level 20 and finding the two magical items with base values of 3 and 5.

exercises/practice/sum-of-multiples/.docs/introduction.md

@@ -0,0 +1,6 @@
+# Introduction
+
+You work for a company that makes an online, fantasy-survival game.
+
+When a player finishes a level, they are awarded energy points.
+The amount of energy awarded depends on which magical items the player found while exploring that level.

exercises/practice/sum-of-multiples/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "sum-of-multiples.coffee"
+    ],
+    "test": [
+      "sum-of-multiples.spec.coffee"
+    ],
+    "example": [
+      ".meta/example.coffee"
+    ]
+  },
+  "blurb": "Given a number, find the sum of all the multiples of particular numbers up to but not including that number.",
+  "source": "A variation on Problem 1 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=1"
+}

exercises/practice/sum-of-multiples/.meta/example.coffee

@@ -0,0 +1,13 @@
+class SumOfMultiples
+  @sum: (factors, limit) ->
+    multiples = []
+    for i in [1..limit - 1]
+      for factor in factors
+        if i % factor is 0
+          multiples.push i
+          break
+    multiples.reduce (a, b) ->
+      a + b
+    , 0
+
+module.exports = SumOfMultiples

exercises/practice/sum-of-multiples/.meta/tests.toml

@@ -0,0 +1,58 @@
+# 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.
+
+[54aaab5a-ce86-4edc-8b40-d3ab2400a279]
+description = "no multiples within limit"
+
+[361e4e50-c89b-4f60-95ef-5bc5c595490a]
+description = "one factor has multiples within limit"
+
+[e644e070-040e-4ae0-9910-93c69fc3f7ce]
+description = "more than one multiple within limit"
+
+[607d6eb9-535c-41ce-91b5-3a61da3fa57f]
+description = "more than one factor with multiples within limit"
+
+[f47e8209-c0c5-4786-b07b-dc273bf86b9b]
+description = "each multiple is only counted once"
+
+[28c4b267-c980-4054-93e9-07723db615ac]
+description = "a much larger limit"
+
+[09c4494d-ff2d-4e0f-8421-f5532821ee12]
+description = "three factors"
+
+[2d0d5faa-f177-4ad6-bde9-ebb865083751]
+description = "factors not relatively prime"
+
+[ece8f2e8-96aa-4166-bbb7-6ce71261e354]
+description = "some pairs of factors relatively prime and some not"
+
+[624fdade-6ffb-400e-8472-456a38c171c0]
+description = "one factor is a multiple of another"
+
+[949ee7eb-db51-479c-b5cb-4a22b40ac057]
+description = "much larger factors"
+
+[41093673-acbd-482c-ab80-d00a0cbedecd]
+description = "all numbers are multiples of 1"
+
+[1730453b-baaa-438e-a9c2-d754497b2a76]
+description = "no factors means an empty sum"
+
+[214a01e9-f4bf-45bb-80f1-1dce9fbb0310]
+description = "the only multiple of 0 is 0"
+
+[c423ae21-a0cb-4ec7-aeb1-32971af5b510]
+description = "the factor 0 does not affect the sum of multiples of other factors"
+
+[17053ba9-112f-4ac0-aadb-0519dd836342]
+description = "solutions using include-exclude must extend to cardinality greater than 3"

exercises/practice/sum-of-multiples/sum-of-multiples.coffee

@@ -0,0 +1,4 @@
+class SumOfMultiples
+  @sum: (factors, limit) ->
+
+module.exports = SumOfMultiples

exercises/practice/sum-of-multiples/sum-of-multiples.spec.coffee

@@ -0,0 +1,50 @@
+SumOfMultiples = require './sum-of-multiples'
+
+describe 'Sum of Multiples', ->
+  it 'no multiples within limit', ->
+    expect(SumOfMultiples.sum [3, 5], 1).toEqual 0
+
+  xit 'one factor has multiples within limit', ->
+    expect(SumOfMultiples.sum [3, 5], 4).toEqual 3
+
+  xit 'more than one multiple within limit', ->
+    expect(SumOfMultiples.sum [3], 7).toEqual 9
+
+  xit 'more than one factor with multiples within limit', ->
+    expect(SumOfMultiples.sum [3, 5], 10).toEqual 23
+
+  xit 'each multiple is only counted once', ->
+    expect(SumOfMultiples.sum [3, 5], 100).toEqual 2318
+
+  xit 'a much larger limit', ->
+    expect(SumOfMultiples.sum [3, 5], 1000).toEqual 233168
+
+  xit 'three factors', ->
+    expect(SumOfMultiples.sum [7, 13, 17], 20).toEqual 51
+
+  xit 'factors not relatively prime', ->
+    expect(SumOfMultiples.sum [4, 6], 15).toEqual 30
+
+  xit 'some pairs of factors relatively prime and some not', ->
+    expect(SumOfMultiples.sum [5, 6, 8], 150).toEqual 4419
+
+  xit 'one factor is a multiple of another', ->
+    expect(SumOfMultiples.sum [5, 25], 51).toEqual 275
+
+  xit 'much larger factors', ->
+    expect(SumOfMultiples.sum [43, 47], 10000).toEqual 2203160
+
+  xit 'all numbers are multiples of 1', ->
+    expect(SumOfMultiples.sum [1], 100).toEqual 4950
+
+  xit 'no factors means an empty sum', ->
+    expect(SumOfMultiples.sum [], 10000).toEqual 0
+
+  xit 'the only multiple of 0 is 0', ->
+    expect(SumOfMultiples.sum [0], 1).toEqual 0
+
+  xit 'the factor 0 does not affect the sum of multiples of other factors', ->
+    expect(SumOfMultiples.sum [3, 0], 4).toEqual 3
+
+  xit 'solutions using include-exclude must extend to cardinality greater than 3', ->
+    expect(SumOfMultiples.sum [2, 3, 5, 7, 11], 10000).toEqual 39614537