Trie

Trie/Trie/Trie.cs

@@ -0,0 +1,154 @@
+namespace TrieClass
+{
+    /// <summary>
+    /// Trie class.
+    /// </summary>
+    public class Trie
+    {
+        private readonly Dictionary<char, Trie> children;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Trie"/> class.
+        /// </summary>
+        public Trie()
+        {
+            this.children = [];
+            this.IsTerminal = false;
+            this.CountOfTerminalsFarther = 0;
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether the edge is terminal.
+        /// </summary>
+        public bool IsTerminal { get; private set; }
+
+        /// <summary>
+        /// Gets the trie size.
+        /// </summary>
+        public int Size => this.CountOfTerminalsFarther;
+
+        private int CountOfTerminalsFarther { get; set; }
+
+        /// <summary>
+        /// Adds given string to trie.
+        /// </summary>
+        /// <param name="element">String to add to the trie.</param>
+        /// <returns>True if successful, otherwise false.</returns>
+        public bool Add(string element)
+        {
+            if (element.Length == 0)
+            {
+                if (this.IsTerminal)
+                {
+                    return false;
+                }
+
+                this.IsTerminal = true;
+                this.CountOfTerminalsFarther++;
+
+                return true;
+            }
+
+            if (!this.children.TryGetValue(element[0], out Trie? child))
+            {
+                child = new Trie();
+                this.children.Add(element[0], child);
+            }
+
+            if (child.Add(element[1..]))
+            {
+                this.CountOfTerminalsFarther++;
+
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Checks whether the element is contained in the trie.
+        /// </summary>
+        /// <param name="element">The element that needs to be checked if it is in the trie.</param>
+        /// <returns>True if successful, otherwise false.</returns>
+        public bool Contains(string element)
+        {
+            Trie? result = this.FindEdgeWithKey(element);
+
+            return result != null && result.IsTerminal;
+        }
+
+        /// <summary>
+        /// Removes an element from the trie.
+        /// </summary>
+        /// <param name="element">The element to be removed from the trie.</param>
+        /// <returns>True if successful, otherwise false.</returns>
+        public bool Remove(string element)
+        {
+            if (element.Length == 0)
+            {
+                if (!this.IsTerminal)
+                {
+                    return false;
+                }
+
+                this.CountOfTerminalsFarther--;
+                this.IsTerminal = false;
+
+                return true;
+            }
+
+            if (!this.children.TryGetValue(element[0], out Trie? value))
+            {
+                return false;
+            }
+
+            if (value.Remove(element[1..]))
+            {
+                this.CountOfTerminalsFarther--;
+                if (value.CountOfTerminalsFarther == 0)
+                {
+                    this.children.Remove(element[0]);
+                }
+
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Searches for how many trie elements start with a given prefix.
+        /// </summary>
+        /// <param name="prefix">The prefix for the search.</param>
+        /// <returns>The number of elements starting with this prefix.</returns>
+        public int HowManyStartsWithPrefix(string prefix)
+        {
+            if (prefix.Length == 0)
+            {
+                return this.CountOfTerminalsFarther;
+            }
+
+            if (!this.children.TryGetValue(prefix[0], out Trie? edge))
+            {
+                return 0;
+            }
+
+            return edge.HowManyStartsWithPrefix(prefix[1..]);
+        }
+
+        private Trie? FindEdgeWithKey(string key)
+        {
+            if (key.Length == 0)
+            {
+                return this;
+            }
+
+            if (!this.children.TryGetValue(key[0], out Trie? child))
+            {
+                return null;
+            }
+
+            return child.FindEdgeWithKey(key[1..]);
+        }
+    }
+}

Trie/Trie/Trie.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

Trie/Trie/Trie.sln

@@ -0,0 +1,31 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.9.34607.119
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Trie", "Trie.csproj", "{B7F7A03C-3413-46A2-B23F-23680C6067B2}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TrieTests", "..\TrieTests\TrieTests.csproj", "{1C42C607-28FA-4520-A656-ABA4702B9BBA}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{B7F7A03C-3413-46A2-B23F-23680C6067B2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B7F7A03C-3413-46A2-B23F-23680C6067B2}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B7F7A03C-3413-46A2-B23F-23680C6067B2}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B7F7A03C-3413-46A2-B23F-23680C6067B2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{1C42C607-28FA-4520-A656-ABA4702B9BBA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1C42C607-28FA-4520-A656-ABA4702B9BBA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1C42C607-28FA-4520-A656-ABA4702B9BBA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1C42C607-28FA-4520-A656-ABA4702B9BBA}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {FE822E7C-39B7-4707-B1DA-DB3584687258}
+	EndGlobalSection
+EndGlobal

Trie/TrieTests/TrieTest.cs

@@ -0,0 +1,61 @@
+using TrieClass;
+
+[TestFixture]
+public class TrieTests
+{
+    private Trie trie;
+
+    [SetUp]
+    public void Setup()
+    {
+        trie = new Trie();
+    }
+
+    [Test]
+    public void AddElement_ReturnsTrue()
+    {
+        Assert.IsTrue(trie.Add("hello"));
+    }
+
+    [Test]
+    public void AddExistingElement_ReturnsFalse()
+    {
+        trie.Add("hello");
+        Assert.IsFalse(trie.Add("hello"));
+    }
+
+    [Test]
+    public void ContainsElement_ReturnsTrue()
+    {
+        trie.Add("world");
+        Assert.IsTrue(trie.Contains("world"));
+    }
+
+    [Test]
+    public void DoesNotContainElement_ReturnsFalse()
+    {
+        Assert.IsFalse(trie.Contains("world"));
+    }
+
+    [Test]
+    public void RemoveElement_ReturnsTrue()
+    {
+        trie.Add("apple");
+        Assert.IsTrue(trie.Remove("apple"));
+    }
+
+    [Test]
+    public void RemoveNotExistingElement_ReturnsFalse()
+    {
+        Assert.IsFalse(trie.Remove("hello"));
+    }
+
+    [Test]
+    public void HowManyStartsWithPrefix_ReturnsCorrectCount()
+    {
+        trie.Add("cat");
+        trie.Add("car");
+        trie.Add("dog");
+        Assert.That(trie.HowManyStartsWithPrefix("c"), Is.EqualTo(2));
+    }
+}

Trie/TrieTests/TrieTests.csproj

@@ -0,0 +1,36 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <None Include="..\Trie\.editorconfig" Link=".editorconfig" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="Microsoft.Playwright.NUnit" Version="1.27.1" />
+    <PackageReference Include="NUnit" Version="3.14.0" />
+    <PackageReference Include="NUnit.Analyzers" Version="3.9.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Trie\Trie.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Microsoft.Playwright.NUnit" />
+    <Using Include="NUnit.Framework" />
+    <Using Include="System.Text.RegularExpressions" />
+    <Using Include="System.Threading.Tasks" />
+  </ItemGroup>
+
+</Project>