Add satellite exercise (#2383)

exercism · Feb 15, 2025 · 978bf64 · 978bf64
1 parent 8729d74
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diff --git a/config.json b/config.json
@@ -2675,6 +2675,20 @@
           "numbers"
         ],
         "difficulty": 7
+      },
+      {
+        "slug": "satellite",
+        "name": "Satellite",
+        "uuid": "4da2ca3b-2fe5-4048-985b-95a3b24aaa36",
+        "practices": [
+          "for-loops"
+        ],
+        "prerequisites": [
+          "generic-methods",
+          "chars",
+          "for-loops"
+        ],
+        "difficulty": 7
       }
     ],
     "foregone": [

diff --git a/exercises/Exercises.sln b/exercises/Exercises.sln
@@ -351,6 +351,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "KillerSudokuHelper", "pract
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SquareRoot", "practice\square-root\SquareRoot.csproj", "{5C05051E-D46C-4544-9CF8-F2A748F63172}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Satellite", "practice\satellite\Satellite.csproj", "{8E276065-1371-4CFA-BA20-95225EC6AEBC}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -1045,6 +1047,10 @@ Global
 		{BEBBD420-075D-46F1-AE51-CC9A05FECE4A}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{BEBBD420-075D-46F1-AE51-CC9A05FECE4A}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{BEBBD420-075D-46F1-AE51-CC9A05FECE4A}.Release|Any CPU.Build.0 = Release|Any CPU
+		{8E276065-1371-4CFA-BA20-95225EC6AEBC}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8E276065-1371-4CFA-BA20-95225EC6AEBC}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8E276065-1371-4CFA-BA20-95225EC6AEBC}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8E276065-1371-4CFA-BA20-95225EC6AEBC}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1222,6 +1228,7 @@ Global
 		{90C70CAA-A225-4D66-8B42-6AC82AD1D5DC} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
 		{5C05051E-D46C-4544-9CF8-F2A748F63172} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
 		{BEBBD420-075D-46F1-AE51-CC9A05FECE4A} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
+		{8E276065-1371-4CFA-BA20-95225EC6AEBC} = {E276EF69-669A-43E0-88AC-8ABB17A9C026}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {AB4EA6C9-5461-4024-BDC7-2AE0C3A85CD1}

diff --git a/exercises/practice/satellite/.docs/instructions.md b/exercises/practice/satellite/.docs/instructions.md
@@ -0,0 +1,27 @@
+# Instructions
+
+Imagine you need to transmit a binary tree to a satellite approaching Alpha Centauri and you have limited bandwidth.
+Since the tree has no repeating items it can be uniquely represented by its [pre-order and in-order traversals][wiki].
+
+Write the software for the satellite to rebuild the tree from the traversals.
+
+A pre-order traversal reads the value of the current node before (hence "pre") reading the left subtree in pre-order.
+Afterwards the right subtree is read in pre-order.
+
+An in-order traversal reads the left subtree in-order then the current node and finally the right subtree in-order.
+So in order from left to right.
+
+For example the pre-order traversal of this tree is [a, i, x, f, r].
+The in-order traversal of this tree is [i, a, f, x, r]
+
+```text
+  a
+ / \
+i   x
+   / \
+  f   r
+```
+
+Note: the first item in the pre-order traversal is always the root.
+
+[wiki]: https://en.wikipedia.org/wiki/Tree_traversal
diff --git a/exercises/practice/satellite/.editorconfig b/exercises/practice/satellite/.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
+
+[Satellite.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
diff --git a/exercises/practice/satellite/.meta/Example.cs b/exercises/practice/satellite/.meta/Example.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Linq;
+
+public record Tree(char Value, Tree Left, Tree Right);
+
+public static class Satellite
+{
+    public static Tree TreeFromTraversals(char[] preOrder, char[] inOrder)
+    {
+        if (preOrder.Length != inOrder.Length) throw new ArgumentException("Traversals must have the same length");
+        if (!preOrder.Order().SequenceEqual(inOrder.Order())) throw new ArgumentException("Traversals must be consistent");
+        if (preOrder.Distinct().Count() != preOrder.Length) throw new ArgumentException("Traversals must not have repeated items");
+
+        int preOrderIndex = 0;
+        return TreeFromTraversals(preOrder, inOrder, ref preOrderIndex, 0, preOrder.Length - 1);
+    }
+
+    private static Tree TreeFromTraversals(char[] preOrder, char[] inOrder, ref int preOrderIndex, int left, int right)
+    {
+        if (left > right) return null;
+
+        var preOrderValue = preOrder[preOrderIndex++];
+        var inOrderIndex = Array.IndexOf(inOrder, preOrderValue);
+
+        return new Tree(
+            preOrderValue,
+            TreeFromTraversals(preOrder, inOrder, ref preOrderIndex, left, inOrderIndex - 1),
+            TreeFromTraversals(preOrder, inOrder, ref preOrderIndex, inOrderIndex + 1, right));
+    }
+}
diff --git a/exercises/practice/satellite/.meta/Generator.tpl b/exercises/practice/satellite/.meta/Generator.tpl
@@ -0,0 +1,36 @@
+{{ func to_tree
+    if $0.empty?
+        ret "null"
+    end
+
+    ret $"new Tree('{$0.v}', {to_tree $0.l}, {to_tree $0.r})"
+end }}
+
+{{ func to_arg
+    if $0.empty?
+        ret "[]"
+    end
+
+    ret "['" + (array.join $0 "', '") + "']"
+end }}
+
+using System;
+using Xunit;
+
+public class {{ testClass }}
+{
+    {{- for test in tests }}
+    [Fact{{ if !for.first }}(Skip = "Remove this Skip property to run this test"){{ end }}]
+    public void {{ test.testMethod }}()
+    {
+        {{- if test.expected.error }}
+            Assert.Throws<ArgumentException>(() => {{ testedClass }}.{{ test.testedMethod }}({{ test.input.preorder | to_arg }}, {{ test.input.inorder | to_arg }}));
+        {{- else if test.expected.empty? }}
+            Assert.Null({{ testedClass }}.{{ test.testedMethod }}({{ test.input.preorder | to_arg }}, {{ test.input.inorder | to_arg }}));
+        {{ else }}
+            var expected = {{ test.expected | to_tree }};
+            Assert.Equal(expected, {{ testedClass }}.{{ test.testedMethod }}({{ test.input.preorder | to_arg }}, {{ test.input.inorder | to_arg }}));
+        {{ end -}}
+    }
+    {{ end -}}
+}
diff --git a/exercises/practice/satellite/.meta/config.json b/exercises/practice/satellite/.meta/config.json
@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "Satellite.cs"
+    ],
+    "test": [
+      "SatelliteTests.cs"
+    ],
+    "example": [
+      ".meta/Example.cs"
+    ]
+  },
+  "blurb": "Rebuild binary trees from pre-order and in-order traversals."
+}
diff --git a/exercises/practice/satellite/.meta/tests.toml b/exercises/practice/satellite/.meta/tests.toml
@@ -0,0 +1,28 @@
+# 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.
+
+[8df3fa26-811a-4165-9286-ff9ac0850d19]
+description = "Empty tree"
+
+[f945ccfc-05e3-47d7-825b-0270559d43ad]
+description = "Tree with one item"
+
+[a0121d5f-37b0-48dd-9c64-cba4c4464135]
+description = "Tree with many items"
+
+[6074041f-4891-4d81-a128-401050c2a3b0]
+description = "Reject traversals of different length"
+
+[27916ce4-45f3-4d8b-8528-496fedc157ca]
+description = "Reject inconsistent traversals of same length"
+
+[d86a3d72-76a9-43b5-9d3a-e64cb1216035]
+description = "Reject traversals with repeated items"
diff --git a/exercises/practice/satellite/Satellite.cs b/exercises/practice/satellite/Satellite.cs
@@ -0,0 +1,11 @@
+using System;
+
+public record Tree(char Value, Tree Left, Tree Right);
+
+public static class Satellite
+{
+    public static Tree TreeFromTraversals(char[] preOrder, char[] inOrder)
+    {
+        throw new NotImplementedException("You need to implement this method.");
+    }
+}
diff --git a/exercises/practice/satellite/Satellite.csproj b/exercises/practice/satellite/Satellite.csproj
@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Exercism.Tests" Version="0.1.0-beta1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="xunit" Version="2.8.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.0.1">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+
+</Project>