Counting Sort: net10.0, copy-per-call benchmark, stable counting sort

csharp-algorithms/CountingSort/CountingSort/CountingSort.csproj

@@ -2,13 +2,13 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.13.1" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.15.8" />
   </ItemGroup>
 
 </Project>

csharp-algorithms/CountingSort/CountingSort/CountingSortBenchmarks.cs

@@ -0,0 +1,43 @@
+using BenchmarkDotNet.Attributes;
+
+namespace CountingSort;
+
+public class CountingSortBenchmarks
+{
+    private readonly CountingSortMethods _sorter = new();
+    private int[] _source = [];
+    private int[] _work = [];
+
+    [Params("Best Case", "Average Case", "Worst Case")]
+    public string Input { get; set; } = "Average Case";
+
+    [GlobalSetup]
+    public void Setup()
+    {
+        _source = Input switch
+        {
+            "Best Case" => CountingSortMethods.CreateRandomArray(20_000, 1, 2),
+            "Average Case" => CountingSortMethods.CreateRandomArray(20_000, 10_000, 30_000),
+            _ => CountingSortMethods.CreateImbalancedArray(
+                CountingSortMethods.CreateRandomArray(19_999, 10_000, 30_000))
+        };
+        _work = new int[_source.Length];
+    }
+
+    [Benchmark]
+    public int[] CountingSort()
+    {
+        _source.CopyTo(_work, 0);
+
+        return _sorter.CountingSort(_work);
+    }
+
+    [Benchmark(Baseline = true)]
+    public int[] ArraySort()
+    {
+        _source.CopyTo(_work, 0);
+        Array.Sort(_work);
+
+        return _work;
+    }
+}

csharp-algorithms/CountingSort/CountingSort/CountingSortMethods.cs

@@ -1,79 +1,86 @@
-using BenchmarkDotNet.Attributes;
+namespace CountingSort;
 
-namespace CountingSort
+public class CountingSortMethods
 {
-    public class CountingSortMethods
+    public int[] CountingSort(int[] array)
     {
-        public IEnumerable<object[]> SampleArrays()
+        var size = array.Length;
+        if (size == 0)
+            return array;
+
+        var maxElement = GetMaxVal(array, size);
+        var occurrences = new int[maxElement + 1];
+
+        for (int i = 0; i < size; i++)
         {
-            yield return new object[] { CreateRandomArray(20000, 1, 2), "Best Case" };
-            yield return new object[] { CreateRandomArray(20000, 10000, 30000), "Average Case" };
-            yield return new object[] { CreateImbalancedArray(CreateRandomArray(19999, 10000, 30000)), "Worst Case" };
+            occurrences[array[i]]++;
         }
 
-        [Benchmark]
-        [ArgumentsSource(nameof(SampleArrays))]
-        public int[] CountingSort(int[] array, string arrayName)
+        for (int i = 0, j = 0; i <= maxElement; i++)
         {
-            var size = array.Length;
-            var maxElement = GetMaxVal(array, size);
-            var occurrences = new int[maxElement + 1];
-
-            for (int i = 0; i < maxElement + 1; i++)
+            while (occurrences[i] > 0)
             {
-                occurrences[i] = 0;
+                array[j] = i;
+                j++;
+                occurrences[i]--;
             }
+        }
 
-            for (int i = 0; i < size; i++)
-            {
-                occurrences[array[i]]++;
-            }
+        return array;
+    }
 
-            for (int i = 0, j = 0; i <= maxElement; i++)
-            {
-                while (occurrences[i] > 0)
-                {
-                    array[j] = i;
-                    j++;
-                    occurrences[i]--;
-                }
-            }
+    public static int GetMaxVal(int[] array, int size)
+    {
+        var maxVal = array[0];
 
-            return array;
-        }
+        for (int i = 1; i < size; i++)
+            if (array[i] > maxVal)
+                maxVal = array[i];
 
-        public static int GetMaxVal(int[] array, int size)
-        {
-            var maxVal = array[0];
+        return maxVal;
+    }
 
-            for (int i = 1; i < size; i++)
-                if (array[i] > maxVal)
-                    maxVal = array[i];
+    public static T[] StableCountingSort<T>(T[] items, Func<T, int> getKey)
+    {
+        if (items.Length == 0)
+            return [];
 
-            return maxVal;
-        }
+        var min = items.Min(getKey);
+        var max = items.Max(getKey);
+        var range = (long)max - min + 1;
+        if (range > Array.MaxLength)
+            throw new ArgumentOutOfRangeException(nameof(items), "The key range is too wide for counting sort.");
 
-
-        public static int[] CreateRandomArray(int size, int lower, int upper)
-        {
-            var array = new int[size];
-            var rand = new Random();
+        var counts = new int[range];
 
-            for (int i = 0; i < size; i++)
-                array[i] = rand.Next(lower, upper);
+        foreach (var item in items)
+            counts[getKey(item) - min]++;
 
-            return array;
-        }
+        for (int i = 1; i < counts.Length; i++)
+            counts[i] += counts[i - 1];
+
+        var sorted = new T[items.Length];
 
-        public static int[] CreateImbalancedArray(int[] array)
+        for (int i = items.Length - 1; i >= 0; i--)
         {
-            List<int> numbers = new List<int>();
+            var index = getKey(items[i]) - min;
+            counts[index]--;
+            sorted[counts[index]] = items[i];
+        }
 
-            numbers.AddRange(array);
-            numbers.Add(Int32.MaxValue/2);
+        return sorted;
+    }
 
-            return numbers.ToArray();
-        }
+    public static int[] CreateRandomArray(int size, int lower, int upper)
+    {
+        var array = new int[size];
+        var rand = new Random();
+
+        for (int i = 0; i < size; i++)
+            array[i] = rand.Next(lower, upper);
 
+        return array;
     }
+
+    public static int[] CreateImbalancedArray(int[] array) => [.. array, 2_000_000];
 }

csharp-algorithms/CountingSort/CountingSort/Program.cs

@@ -1,4 +1,4 @@
 using BenchmarkDotNet.Running;
 using CountingSort;
 
-var summary = BenchmarkRunner.Run<CountingSortMethods>();
+BenchmarkRunner.Run<CountingSortBenchmarks>(args: args);

csharp-algorithms/CountingSort/CountingSortTests/CountingSortTests.csproj

@@ -1,18 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="2.2.8" />
-    <PackageReference Include="MSTest.TestFramework" Version="2.2.8" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.11.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="4.5.2" />
+    <PackageReference Include="MSTest.TestFramework" Version="4.5.2" />
+    <PackageReference Include="coverlet.collector" Version="10.1.0" />
   </ItemGroup>
 
   <ItemGroup>