Add knapsack exercise (#1291)

config.json

@@ -2149,6 +2149,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 2
+      },
+      {
+        "slug": "knapsack",
+        "name": "Knapsack",
+        "uuid": "5bfffdf2-95d9-4794-b703-340c253400b2",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
       }
     ],
     "foregone": [

exercises/practice/knapsack/.config/dotnet-tools.json

@@ -0,0 +1,12 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "fantomas-tool": {
+      "version": "4.7.9",
+      "commands": [
+        "fantomas"
+      ]
+    }
+  }
+}

exercises/practice/knapsack/.docs/instructions.md

@@ -0,0 +1,25 @@
+# Instructions
+
+Your task is to determine which items to take so that the total value of his selection is maximized, taking into account the knapsack's carrying capacity.
+
+Items will be represented as a list of items.
+Each item will have a weight and value.
+All values given will be strictly positive.
+Bob can take only one of each item.
+
+For example:
+
+```text
+Items: [
+  { "weight": 5, "value": 10 },
+  { "weight": 4, "value": 40 },
+  { "weight": 6, "value": 30 },
+  { "weight": 4, "value": 50 }
+]
+
+Knapsack Maximum Weight: 10
+```
+
+For the above, the first item has weight 5 and value 10, the second item has weight 4 and value 40, and so on.
+In this example, Bob should take the second and fourth item to maximize his value, which, in this case, is 90.
+He cannot get more than 90 as his knapsack has a weight limit of 10.

exercises/practice/knapsack/.docs/introduction.md

@@ -0,0 +1,8 @@
+# Introduction
+
+Bob is a thief.
+After months of careful planning, he finally manages to crack the security systems of a fancy store.
+
+In front of him are many items, each with a value and weight.
+Bob would gladly take all of the items, but his knapsack can only hold so much weight.
+Bob has to carefully consider which items to take so that the total value of his selection is maximized.

exercises/practice/knapsack/.meta/Example.fs

@@ -0,0 +1,13 @@
+module Knapsack
+
+type Item = { weight: int; value: int }
+
+let rec maximumValue items maximumWeight =
+    match items with
+    | [] -> 0
+    | item :: rest when item.weight > maximumWeight -> maximumValue rest maximumWeight
+    | item :: rest ->
+        max
+            (maximumValue rest maximumWeight)
+            (item.value
+             + maximumValue rest (maximumWeight - item.weight))

exercises/practice/knapsack/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "Knapsack.fs"
+    ],
+    "test": [
+      "KnapsackTests.fs"
+    ],
+    "example": [
+      ".meta/Example.fs"
+    ]
+  },
+  "blurb": "Given a knapsack that can only carry a certain weight, determine which items to put in the knapsack in order to maximize their combined value.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Knapsack_problem"
+}

exercises/practice/knapsack/.meta/tests.toml

@@ -0,0 +1,36 @@
+# 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.
+
+[a4d7d2f0-ad8a-460c-86f3-88ba709d41a7]
+description = "no items"
+include = false
+
+[3993a824-c20e-493d-b3c9-ee8a7753ee59]
+description = "no items"
+reimplements = "a4d7d2f0-ad8a-460c-86f3-88ba709d41a7"
+
+[1d39e98c-6249-4a8b-912f-87cb12e506b0]
+description = "one item, too heavy"
+
+[833ea310-6323-44f2-9d27-a278740ffbd8]
+description = "five items (cannot be greedy by weight)"
+
+[277cdc52-f835-4c7d-872b-bff17bab2456]
+description = "five items (cannot be greedy by value)"
+
+[81d8e679-442b-4f7a-8a59-7278083916c9]
+description = "example knapsack"
+
+[f23a2449-d67c-4c26-bf3e-cde020f27ecc]
+description = "8 items"
+
+[7c682ae9-c385-4241-a197-d2fa02c81a11]
+description = "15 items"

exercises/practice/knapsack/Knapsack.fs

@@ -0,0 +1,6 @@
+module Knapsack
+
+type Item = { weight: int; value: int }
+
+let rec maximumValue items maximumWeight =
+    failwith "Please implement the 'maximumValue' function"

exercises/practice/knapsack/Knapsack.fsproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+    <GenerateProgramFile>false</GenerateProgramFile>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Knapsack.fs" />
+    <Compile Include="KnapsackTests.fs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Exercism.Tests" Version="0.1.0-beta1" />
+    <PackageReference Include="FsUnit.xUnit" Version="4.0.4" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
+    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+</Project>

exercises/practice/knapsack/KnapsackTests.fs

@@ -0,0 +1,81 @@
+module KnapsackTests
+
+open FsUnit.Xunit
+open Xunit
+
+open Knapsack
+
+[<Fact>]
+let ``No items`` () = maximumValue [] 100 |> should equal 0
+
+[<Fact(Skip = "Remove this Skip property to run this test")>]
+let ``One item, too heavy`` () =
+    maximumValue [ { weight = 100; value = 1 } ] 10
+    |> should equal 0
+
+[<Fact(Skip = "Remove this Skip property to run this test")>]
+let ``Five items (cannot be greedy by weight)`` () =
+    maximumValue
+        [ { weight = 2; value = 5 }
+          { weight = 2; value = 5 }
+          { weight = 2; value = 5 }
+          { weight = 2; value = 5 }
+          { weight = 10; value = 21 } ]
+        10
+    |> should equal 21
+
+[<Fact(Skip = "Remove this Skip property to run this test")>]
+let ``Five items (cannot be greedy by value)`` () =
+    maximumValue
+        [ { weight = 2; value = 20 }
+          { weight = 2; value = 20 }
+          { weight = 2; value = 20 }
+          { weight = 2; value = 20 }
+          { weight = 10; value = 50 } ]
+        10
+    |> should equal 80
+
+[<Fact(Skip = "Remove this Skip property to run this test")>]
+let ``Example knapsack`` () =
+    maximumValue
+        [ { weight = 5; value = 10 }
+          { weight = 4; value = 40 }
+          { weight = 6; value = 30 }
+          { weight = 4; value = 50 } ]
+        10
+    |> should equal 90
+
+[<Fact(Skip = "Remove this Skip property to run this test")>]
+let ``8 items`` () =
+    maximumValue
+        [ { weight = 25; value = 350 }
+          { weight = 35; value = 400 }
+          { weight = 45; value = 450 }
+          { weight = 5; value = 20 }
+          { weight = 25; value = 70 }
+          { weight = 3; value = 8 }
+          { weight = 2; value = 5 }
+          { weight = 2; value = 5 } ]
+        104
+    |> should equal 900
+
+[<Fact(Skip = "Remove this Skip property to run this test")>]
+let ``15 items`` () =
+    maximumValue
+        [ { weight = 70; value = 135 }
+          { weight = 73; value = 139 }
+          { weight = 77; value = 149 }
+          { weight = 80; value = 150 }
+          { weight = 82; value = 156 }
+          { weight = 87; value = 163 }
+          { weight = 90; value = 173 }
+          { weight = 94; value = 184 }
+          { weight = 98; value = 192 }
+          { weight = 106; value = 201 }
+          { weight = 110; value = 210 }
+          { weight = 113; value = 214 }
+          { weight = 115; value = 221 }
+          { weight = 118; value = 229 }
+          { weight = 120; value = 240 } ]
+        750
+    |> should equal 1458

generators/Generators.fs

@@ -2041,3 +2041,6 @@ type SquareRoot() =
 
 type EliudsEggs() =
     inherit ExerciseGenerator()
+
+type Knapsack() =
+    inherit ExerciseGenerator()