Add levenshtein

Author: janosorcsik

levenshtein/csharp/code.cs

@@ -0,0 +1,99 @@
+using System.Runtime.CompilerServices;
+
+var runMs = int.Parse(args[0]);
+var warmupMs = int.Parse(args[1]);
+var inputPath = args[2];
+
+var content = File.ReadAllLines(inputPath);
+
+Benchmark<List<int>>.Run(() => Levenshtein(content), warmupMs);
+
+var result = Benchmark<List<int>>.Run(() => Levenshtein(content), runMs);
+
+var summedResult = new BenchmarkResult<int>(
+    result!.MeanMs,
+    result.StdDevMs,
+    result.MinMs,
+    result.MaxMs,
+    result.Runs,
+    result.Result.Sum());
+
+Console.WriteLine(summedResult);
+
+return;
+
+static List<int> Levenshtein(string[] content)
+{
+    var distances = new List<int>();
+
+    for (var i = 0; i < content.Length; i++)
+    {
+        for (var j = i + 1; j < content.Length; j++)
+        {
+            distances.Add(LevenshteinDistance(content[i], content[j]));
+        }
+    }
+
+    return distances;
+}
+
+[MethodImpl(MethodImplOptions.AggressiveOptimization)]
+static int LevenshteinDistance(ReadOnlySpan<char> str1, ReadOnlySpan<char> str2)
+{
+    // Early termination checks
+    if (str1.SequenceEqual(str2))
+    {
+        return 0;
+    }
+
+    if (str1.IsEmpty)
+    {
+        return str2.Length;
+    }
+
+    if (str2.IsEmpty)
+    {
+        return str1.Length;
+    }
+
+    // Ensure str1 is the shorter string
+    if (str1.Length > str2.Length)
+    {
+        var strtemp = str2;
+        str2 = str1;
+        str1 = strtemp;
+    }
+
+    // Create two rows, previous and current
+    Span<int> prev = stackalloc int[str1.Length + 1];
+    Span<int> curr = stackalloc int[str1.Length + 1];
+
+    // initialize the previous row
+    for (var i = 0; i <= str1.Length; i++)
+    {
+        prev[i] = i;
+    }
+
+    // Iterate and compute distance
+    for (var i = 1; i <= str2.Length; i++)
+    {
+        curr[0] = i;
+        for (var j = 1; j <= str1.Length; j++)
+        {
+            var cost = (str1[j - 1] == str2[i - 1]) ? 0 : 1;
+            curr[j] = Math.Min(
+                prev[j] + 1, // Deletion
+                Math.Min(curr[j - 1] + 1, // Insertion
+                    prev[j - 1] + cost) // Substitution
+            );
+        }
+
+        // Swap spans
+        var temp = prev;
+        prev = curr;
+        curr = temp;
+    }
+
+    // Return final distance, stored in prev[m]
+    return prev[str1.Length];
+}

levenshtein/csharp/in-process/code.cs

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net9.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Compile Include="..\..\..\lib\csharp\benchmark.cs">
+            <Link>benchmark.cs</Link>
+        </Compile>
+    </ItemGroup>
+
+</Project>

levenshtein/csharp/in-process/code.csproj

@@ -0,0 +1,80 @@
+using System.Runtime.CompilerServices;
+
+int min_distance = -1;
+int times = 0;
+for (int i = 0; i < args.Length; i++)
+{
+    for (int j = 0; j < args.Length; j++)
+    {
+        if (i != j)
+        {
+            int distance = levenshtein(args[i], args[j]);
+            if (min_distance == -1 || min_distance > distance)
+            {
+                min_distance = distance;
+            }
+            times++;
+        }
+    }
+}
+Console.WriteLine($"times: {times}");
+Console.WriteLine($"min_distance: {min_distance}");
+
+[MethodImpl(MethodImplOptions.AggressiveOptimization)]
+static int levenshtein(ReadOnlySpan<char> str1, ReadOnlySpan<char> str2)
+{
+    // Early termination checks
+    if (str1.SequenceEqual(str2))
+    {
+        return 0;
+    }
+    if (str1.IsEmpty)
+    {
+        return str2.Length;
+    }
+    if (str2.IsEmpty)
+    {
+        return str1.Length;
+    }
+
+    // Ensure str1 is the shorter string
+    if (str1.Length > str2.Length)
+    {
+        var strtemp = str2;
+        str2 = str1;
+        str1 = strtemp;
+    }
+
+    // Create two rows, previous and current
+    Span<int> prev = stackalloc int[str1.Length + 1];
+    Span<int> curr = stackalloc int[str1.Length + 1];
+
+    // initialize the previous row
+    for (int i = 0; i <= str1.Length; i++)
+    {
+        prev[i] = i;
+    }
+
+    // Iterate and compute distance
+    for (int i = 1; i <= str2.Length; i++)
+    {
+        curr[0] = i;
+        for (int j = 1; j <= str1.Length; j++)
+        {
+            int cost = (str1[j - 1] == str2[i - 1]) ? 0 : 1;
+            curr[j] = Math.Min(
+              prev[j] + 1,      // Deletion
+              Math.Min(curr[j - 1] + 1,    // Insertion
+              prev[j - 1] + cost)  // Substitution
+            );
+        }
+
+        // Swap spans
+        var temp = prev;
+        prev = curr;
+        curr = temp;
+    }
+    
+    // Return final distance, stored in prev[m]
+    return prev[str1.Length];
+}

levenshtein/csharp/legacy/code.cs

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -7,10 +7,4 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
-  <ItemGroup>
-    <Compile Include="..\..\lib\csharp\Benchmark.cs">
-      <Link>Benchmark.cs</Link>
-    </Compile>
-  </ItemGroup>
-
-</Project>
+</Project>