Radix Sort in C#: .NET 10, long exponent, negatives and a copy-per-call benchmark

csharp-algorithms/RadixSort/RadixSort/Program.cs

@@ -1,4 +1,4 @@
 using BenchmarkDotNet.Running;
 using RadixSort;
 
-var summary = BenchmarkRunner.Run<RadixSortMethods>();
+BenchmarkRunner.Run<RadixSortBenchmarks>(args: args);

csharp-algorithms/RadixSort/RadixSort/RadixSort.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/RadixSort/RadixSort/RadixSortBenchmarks.cs

@@ -0,0 +1,43 @@
+using BenchmarkDotNet.Attributes;
+
+namespace RadixSort;
+
+public class RadixSortBenchmarks
+{
+    private readonly RadixSortMethods _radix = new();
+    private int[] _source = [];
+    private int[] _work = [];
+
+    [Params("Random", "Sorted", "Imbalanced")]
+    public string Input { get; set; } = "Random";
+
+    [GlobalSetup]
+    public void Setup()
+    {
+        _source = Input switch
+        {
+            "Sorted" => RadixSortMethods.CreateSortedArray(20000),
+            "Imbalanced" => RadixSortMethods.CreateImbalancedArray(
+                RadixSortMethods.CreateRandomArray(19999, 10000, 30000)),
+            _ => RadixSortMethods.CreateRandomArray(20000, 10000, 30000)
+        };
+        _work = new int[_source.Length];
+    }
+
+    [Benchmark(Baseline = true)]
+    public int[] RadixSort()
+    {
+        _source.CopyTo(_work, 0);
+
+        return _radix.RadixSort(_work, _work.Length);
+    }
+
+    [Benchmark]
+    public int[] ArraySort()
+    {
+        _source.CopyTo(_work, 0);
+        Array.Sort(_work);
+
+        return _work;
+    }
+}

csharp-algorithms/RadixSort/RadixSort/RadixSortMethods.cs

@@ -1,93 +1,108 @@
-using BenchmarkDotNet.Attributes;
+namespace RadixSort;
 
-namespace RadixSort
+public class RadixSortMethods
 {
-    public class RadixSortMethods
+    public int[] RadixSort(int[] array, int size)
     {
-        public IEnumerable<object[]> SampleArrays()
-        {
-            yield return new object[] { CreateRandomArray(20000, 10000, 30000), 20000, "Best Case" };
-            yield return new object[] { CreateSortedArray(20000), 20000, "Average Case" };
-            yield return new object[] { CreateImbalancedArray(CreateRandomArray(19999, 10000, 30000)), 20000, "Worst Case" };
-        }
+        if (size == 0)
+            return array;
 
-        [Benchmark]
-        [ArgumentsSource(nameof(SampleArrays))]
-        public int[] RadixSort (int[] array, int size, string arrayName)
-        {
-            var maxVal = GetMaxVal(array, size);
+        var maxVal = GetMaxVal(array, size);
+
+        for (long exponent = 1; maxVal / exponent > 0; exponent *= 10)
+            CountingSort(array, size, exponent);
 
-            for (int exponent = 1; maxVal / exponent > 0; exponent *= 10)
-                CountingSort(array, size, exponent);
+        return array;
+    }
 
+    public int[] RadixSortWithNegatives(int[] array, int size)
+    {
+        if (size == 0)
             return array;
-        }
 
-        public static int GetMaxVal(int[] array, int size)
-        {
-            var maxVal = array[0];
+        var minVal = GetMinVal(array, size);
 
-            for (int i = 1; i < size; i++)
-                if (array[i] > maxVal)
-                    maxVal = array[i];
+        if (minVal >= 0)
+            return RadixSort(array, size);
 
-            return maxVal;
-        }
+        for (int i = 0; i < size; i++)
+            array[i] = checked(array[i] - minVal);
 
-        public static void CountingSort(int[] array, int size, int exponent)
-        {
-            var outputArr = new int[size];
-            var occurences = new int[10];
+        RadixSort(array, size);
 
-            for (int i = 0; i < 10; i++)
-                occurences[i] = 0;
+        for (int i = 0; i < size; i++)
+            array[i] += minVal;
 
-            for (int i = 0; i < size; i++)
-                occurences[(array[i] / exponent) % 10]++;
+        return array;
+    }
 
-            for (int i = 1; i < 10; i++)
-                occurences[i] += occurences[i - 1];
+    public static int GetMaxVal(int[] array, int size)
+    {
+        var maxVal = array[0];
 
-            for (int i = size - 1; i >= 0; i--)
-            {
-                outputArr[occurences[(array[i] / exponent) % 10] - 1] = array[i];
-                occurences[(array[i] / exponent) % 10]--;
-            }
+        for (int i = 1; i < size; i++)
+            if (array[i] > maxVal)
+                maxVal = array[i];
 
-            for (int i = 0; i < size; i++)
-                array[i] = outputArr[i];
-        }
+        return maxVal;
+    }
 
-        public static int[] CreateRandomArray(int size, int lower, int upper)
-        {
-            var array = new int[size];
-            var rand = new Random();
+    public static int GetMinVal(int[] array, int size)
+    {
+        var minVal = array[0];
 
-            for (int i = 0; i < size; i++)
-                array[i] = rand.Next(lower, upper);
+        for (int i = 1; i < size; i++)
+            if (array[i] < minVal)
+                minVal = array[i];
 
-            return array;
-        }
+        return minVal;
+    }
 
-        public static int[] CreateSortedArray(int size)
-        {
-            var array = new int[size];
+    public static void CountingSort(int[] array, int size, long exponent)
+    {
+        var outputArr = new int[size];
+        var occurrences = new int[10];
 
-            for (int i = 0; i < size; i++)
-                array[i] = i;
+        for (int i = 0; i < size; i++)
+            occurrences[(array[i] / exponent) % 10]++;
 
-            return array;
-        }
+        for (int i = 1; i < 10; i++)
+            occurrences[i] += occurrences[i - 1];
 
-        public static int[] CreateImbalancedArray(int[] array)
+        for (int i = size - 1; i >= 0; i--)
         {
-            List<int> numbers = new List<int>();
+            outputArr[occurrences[(array[i] / exponent) % 10] - 1] = array[i];
+            occurrences[(array[i] / exponent) % 10]--;
+        }
 
-            numbers.AddRange(array);
-            numbers.Add(Int32.MaxValue);
+        for (int i = 0; i < size; i++)
+            array[i] = outputArr[i];
+    }
 
-            return numbers.ToArray();
-        }
+    public static int[] CreateRandomArray(int size, int lower, int upper)
+    {
+        var array = new int[size];
+
+        for (int i = 0; i < size; i++)
+            array[i] = Random.Shared.Next(lower, upper);
+
+        return array;
+    }
+
+    public static int[] CreateSortedArray(int size)
+    {
+        var array = new int[size];
+
+        for (int i = 0; i < size; i++)
+            array[i] = i;
+
+        return array;
+    }
+
+    public static int[] CreateImbalancedArray(int[] array)
+    {
+        List<int> numbers = [.. array, int.MaxValue];
 
+        return numbers.ToArray();
     }
 }

csharp-algorithms/RadixSort/RadixSortTests/RadixSortTests.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>