Add knapsack exercise

config.json

@@ -2634,6 +2634,20 @@
           "bit-manipulation"
         ],
         "difficulty": 3
+      },
+      {
+        "slug": "knapsack",
+        "name": "Knapsack",
+        "uuid": "677c9cf8-d94c-423c-aba1-45ff19805655",
+        "practices": [
+          "tuples"
+        ],
+        "prerequisites": [
+          "numbers",
+          "arrays",
+          "tuples"
+        ],
+        "difficulty": 5
       }
     ],
     "foregone": [

exercises/Exercises.sln

@@ -344,6 +344,7 @@ EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "LogAnalysis", "concept\log-analysis\LogAnalysis.csproj", "{D66F4A88-0765-4D6B-A8A4-933E5882EC92}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EliudsEggs", "practice\eliuds-eggs\EliudsEggs.csproj", "{2F3B7384-F4CA-4925-B07C-E05DB3FAC01B}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Knapsack", "practice\knapsack\Knapsack.csproj", "{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -1027,6 +1028,10 @@ Global
 		{2F3B7384-F4CA-4925-B07C-E05DB3FAC01B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{2F3B7384-F4CA-4925-B07C-E05DB3FAC01B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{2F3B7384-F4CA-4925-B07C-E05DB3FAC01B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1201,6 +1206,7 @@ Global
 		{82C5DF7B-6F86-40D3-8F65-4B63D41E23A5} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
 		{D66F4A88-0765-4D6B-A8A4-933E5882EC92} = {3303F74B-62AC-47B7-A8AA-F93A52A1C95C}
 		{2F3B7384-F4CA-4925-B07C-E05DB3FAC01B} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
+		{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {AB4EA6C9-5461-4024-BDC7-2AE0C3A85CD1}

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

@@ -0,0 +1,35 @@
+# Instructions
+
+In this exercise, let's try to solve a classic problem.
+
+Bob is a thief.
+After months of careful planning, he finally manages to crack the security systems of a high-class apartment.
+
+In front of him are many items, each with a value (v) and weight (w).
+Bob, of course, wants to maximize the total value he can get; he would gladly take all of the items if he could.
+However, to his horror, he realizes that the knapsack he carries with him can only hold so much weight (W).
+
+Given a knapsack with a specific carrying capacity (W), help Bob determine the maximum value he can get from the items in the house.
+Note that Bob can take only one of each item.
+
+All values given will be strictly positive.
+Items will be represented as a list of items.
+Each item will have a weight and value.
+
+For example:
+
+```none
+Items: [
+  { "weight": 5, "value": 10 },
+  { "weight": 4, "value": 40 },
+  { "weight": 6, "value": 30 },
+  { "weight": 4, "value": 50 }
+]
+
+Knapsack Limit: 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/.editorconfig

@@ -0,0 +1,141 @@
+###############################
+# Core EditorConfig Options   #
+###############################
+
+; This file is for unifying the coding style for different editors and IDEs.
+; More information at:
+; https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-code-style-settings-reference?view=vs-2017
+; https://docs.microsoft.com/en-us/visualstudio/ide/create-portable-custom-editor-options?view=vs-2017
+
+root = true
+
+[*]
+indent_style = space
+
+[Knapsack.cs]
+indent_size = 4
+
+###############################
+# .NET Coding Conventions     #
+###############################
+
+# Organize usings
+dotnet_sort_system_directives_first = true
+dotnet_separate_import_directive_groups = true
+
+# this. preferences
+dotnet_style_qualification_for_field = false:suggestion
+dotnet_style_qualification_for_property = false:suggestion
+dotnet_style_qualification_for_method = false:suggestion
+dotnet_style_qualification_for_event = false:suggestion
+
+# Language keywords vs BCL types preferences
+dotnet_style_predefined_type_for_locals_parameters_members = true:suggestion
+dotnet_style_predefined_type_for_member_access = true:suggestion
+
+# Parentheses preferences
+dotnet_style_parentheses_in_arithmetic_binary_operators = never_if_unnecessary:none
+dotnet_style_parentheses_in_relational_binary_operators = never_if_unnecessary:none
+dotnet_style_parentheses_in_other_binary_operators = never_if_unnecessary:none
+dotnet_style_parentheses_in_other_operators = never_if_unnecessary:suggestion
+
+# Modifier preferences
+dotnet_style_require_accessibility_modifiers = always:suggestion
+dotnet_style_readonly_field = true:suggestion
+
+# Expression-level preferences
+dotnet_style_object_initializer = true:suggestion
+dotnet_style_collection_initializer = true:suggestion
+dotnet_style_explicit_tuple_names = true:suggestion
+dotnet_style_prefer_inferred_tuple_names = true:suggestion
+dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
+dotnet_style_prefer_auto_properties = true:suggestion
+dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggestion
+dotnet_style_prefer_conditional_expression_over_assignment = true:suggestion
+dotnet_style_prefer_conditional_expression_over_return = true:suggestion
+dotnet_style_coalesce_expression = true:suggestion
+dotnet_style_null_propagation = true:suggestion
+
+###############################
+# Naming Conventions          #
+###############################
+
+# Style Definitions
+dotnet_naming_style.pascal_case_style.capitalization = pascal_case
+
+# Use PascalCase for constant fields
+dotnet_naming_rule.constant_fields_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.constant_fields_should_be_pascal_case.symbols = constant_fields
+dotnet_naming_rule.constant_fields_should_be_pascal_case.style = pascal_case_style
+dotnet_naming_symbols.constant_fields.applicable_kinds = field
+dotnet_naming_symbols.constant_fields.applicable_accessibilities = *
+dotnet_naming_symbols.constant_fields.required_modifiers = const
+
+###############################
+# C# Code Style Rules         #
+###############################
+
+# var preferences
+csharp_style_var_for_built_in_types = true:none
+csharp_style_var_when_type_is_apparent = true:none
+csharp_style_var_elsewhere = true:none
+
+# Expression-bodied members
+csharp_style_expression_bodied_methods = true:suggestion
+csharp_style_expression_bodied_constructors = true:suggestion
+csharp_style_expression_bodied_operators = true:suggestion
+csharp_style_expression_bodied_properties = true:suggestion
+csharp_style_expression_bodied_indexers = true:suggestion
+csharp_style_expression_bodied_accessors = true:suggestion
+
+# Pattern-matching preferences
+csharp_style_pattern_matching_over_is_with_cast_check = true:suggestion
+csharp_style_pattern_matching_over_as_with_null_check = true:suggestion
+
+# Null-checking preferences
+csharp_style_throw_expression = true:suggestion
+csharp_style_conditional_delegate_call = true:suggestion
+
+# Modifier preferences
+csharp_preferred_modifier_order = public,private,protected,internal,static,extern,new,virtual,abstract,sealed,override,readonly,unsafe,volatile,async:suggestion
+
+# Expression-level preferences
+csharp_prefer_braces = true:none
+csharp_prefer_simple_default_expression = true:suggestion
+csharp_style_deconstructed_variable_declaration = true:suggestion
+csharp_style_pattern_local_over_anonymous_function = true:suggestion
+csharp_style_inlined_variable_declaration = true:suggestion
+
+###############################
+# C# Formatting Rules         #
+###############################
+
+# New line preferences
+csharp_new_line_before_open_brace = all
+csharp_new_line_before_else = true
+csharp_new_line_before_catch = true
+csharp_new_line_before_finally = true
+csharp_new_line_before_members_in_object_initializers = false
+csharp_new_line_before_members_in_anonymous_types = false
+csharp_new_line_between_query_expression_clauses = true
+
+# Indentation preferences
+csharp_indent_case_contents = true
+csharp_indent_switch_labels = true
+csharp_indent_labels = flush_left
+
+# Space preferences
+csharp_space_after_cast = false
+csharp_space_after_keywords_in_control_flow_statements = true
+csharp_space_between_method_declaration_parameter_list_parentheses = false
+csharp_space_between_method_call_parameter_list_parentheses = false
+csharp_space_before_colon_in_inheritance_clause = true
+csharp_space_after_colon_in_inheritance_clause = true
+csharp_space_around_binary_operators = before_and_after
+csharp_space_between_method_declaration_empty_parameter_list_parentheses = false
+csharp_space_between_method_call_name_and_opening_parenthesis = false
+csharp_space_between_method_call_empty_parameter_list_parentheses = false
+
+# Wrapping preferences
+csharp_preserve_single_line_blocks = true
+csharp_preserve_single_line_statements = true

exercises/practice/knapsack/.meta/Example.cs

@@ -0,0 +1,22 @@
+public static class Knapsack
+{
+    public static int MaximumValue(int maximumWeight, (int weight, int value)[] items)
+    {
+        var maxWeightForSize = new int[items.Length + 1, maximumWeight + 1];
+
+        for (var item = 1; item <= items.Length; item++)
+        {
+            for (var capacity = 1; capacity <= maximumWeight; capacity++)
+            {
+                var maxWithCurrent = 
+                    capacity >= items[item - 1].weight
+                        ? maxWeightForSize[item - 1, capacity - items[item - 1].weight] + items[item - 1].value
+                        : 0;
+
+                maxWeightForSize[item, capacity] = Math.Max(maxWeightForSize[item - 1, capacity], maxWithCurrent);
+            }
+        }
+
+        return maxWeightForSize[items.Length, maximumWeight];
+    }
+}

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "Knapsack.cs"
+    ],
+    "test": [
+      "KnapsackTests.cs"
+    ],
+    "example": [
+      ".meta/Example.cs"
+    ]
+  },
+  "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.cs

@@ -0,0 +1,7 @@
+public static class Knapsack
+{
+    public static int MaximumValue(int maximumWeight, (int weight, int value)[] items)
+    {
+        throw new System.NotImplementedException("You need to implement this method.");
+    }
+}

exercises/practice/knapsack/Knapsack.csproj

@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Exercism.Tests" Version="0.1.0-beta1" />
+    <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>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+</Project>

exercises/practice/knapsack/KnapsackTests.cs

@@ -0,0 +1,58 @@
+using Xunit;
+
+public class KnapsackTests
+{
+    [Fact]
+    public void No_items()
+    {
+        Assert.Equal(0, Knapsack.MaximumValue(100, []));
+    }
+
+    [Fact(Skip = "Remove this Skip property to run this test")]
+    public void One_item_too_heavy()
+    {
+        (int weight, int value)[] items = [(weight: 100, value: 1)];
+        Assert.Equal(0, Knapsack.MaximumValue(10, items));
+    }
+
+    [Fact(Skip = "Remove this Skip property to run this test")]
+    public void Five_items_cannot_be_greedy_by_weight_()
+    {
+        (int weight, int value)[] items = [(weight: 2, value: 5), (weight: 2, value: 5), (weight: 2, value: 5), (weight: 2, value: 5), (weight: 10, value: 21)];
+        Assert.Equal(21, Knapsack.MaximumValue(10, items));
+    }
+
+    [Fact(Skip = "Remove this Skip property to run this test")]
+    public void Five_items_cannot_be_greedy_by_value_()
+    {
+        (int weight, int value)[] items = [(weight: 2, value: 20), (weight: 2, value: 20), (weight: 2, value: 20), (weight: 2, value: 20), (weight: 10, value: 50)];
+        Assert.Equal(80, Knapsack.MaximumValue(10, items));
+    }
+
+    [Fact(Skip = "Remove this Skip property to run this test")]
+    public void Example_knapsack()
+    {
+        (int weight, int value)[] items = [(weight: 5, value: 10), (weight: 4, value: 40), (weight: 6, value: 30), (weight: 4, value: 50)];
+        Assert.Equal(90, Knapsack.MaximumValue(10, items));
+    }
+
+    [Fact(Skip = "Remove this Skip property to run this test")]
+    public void Number_8_items()
+    {
+        (int weight, int value)[] items = [(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)];
+        Assert.Equal(900, Knapsack.MaximumValue(104, items));
+    }
+
+    [Fact(Skip = "Remove this Skip property to run this test")]
+    public void Number_15_items()
+    {
+        (int weight, int value)[] items = [
+            (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)
+        ];
+        Assert.Equal(1458, Knapsack.MaximumValue(750, items));
+    }
+}