From ee71316de8640383a64b05c0953a9384449fd578 Mon Sep 17 00:00:00 2001
From: Jc Calayag <138150245+Jccqt@users.noreply.github.com>
Date: Fri, 11 Jul 2025 14:34:18 +0800
Subject: [PATCH] Add Gnome sort algorithm

---
 .../Sorters/Comparison/GnomeSorterTests.cs    | 27 ++++++++++++
 Algorithms/Sorters/Comparison/GnomeSorter.cs  | 42 +++++++++++++++++++
 README.md                                     |  1 +
 3 files changed, 70 insertions(+)
 create mode 100644 Algorithms.Tests/Sorters/Comparison/GnomeSorterTests.cs
 create mode 100644 Algorithms/Sorters/Comparison/GnomeSorter.cs

diff --git a/Algorithms.Tests/Sorters/Comparison/GnomeSorterTests.cs b/Algorithms.Tests/Sorters/Comparison/GnomeSorterTests.cs
new file mode 100644
index 00000000..fc9cb5a8
--- /dev/null
+++ b/Algorithms.Tests/Sorters/Comparison/GnomeSorterTests.cs
@@ -0,0 +1,27 @@
+using System;
+using Algorithms.Sorters.Comparison;
+using Algorithms.Tests.Helpers;
+using NUnit.Framework;
+
+namespace Algorithms.Tests.Sorters.Comparison;
+
+public static class GnomeSorterTests
+{
+    [Test]
+    public static void ArraySorted(
+        [Random(0, 1000, 100, Distinct = true)]
+        int n)
+    {
+        // Arrange
+        var sorter = new GnomeSorter<int>();
+        var intComparer = new IntComparer();
+        var (correctArray, testArray) = RandomHelper.GetArrays(n);
+
+        // Act
+        sorter.Sort(testArray, intComparer);
+        Array.Sort(correctArray, intComparer);
+
+        // Assert
+        Assert.That(correctArray, Is.EqualTo(testArray));
+    }
+}
diff --git a/Algorithms/Sorters/Comparison/GnomeSorter.cs b/Algorithms/Sorters/Comparison/GnomeSorter.cs
new file mode 100644
index 00000000..28bfeeb2
--- /dev/null
+++ b/Algorithms/Sorters/Comparison/GnomeSorter.cs
@@ -0,0 +1,42 @@
+using System.Collections.Generic;
+
+namespace Algorithms.Sorters.Comparison;
+
+/// <summary>
+///     Class that implements gnome sort algorithm.
+/// </summary>
+/// <typeparam name="T">Type of array element.</typeparam>
+public class GnomeSorter<T> : IComparisonSorter<T>
+{
+    /// <summary>
+    ///     Moves forward through the array until it founds two elements out of order,
+    ///     then swaps them and move back one position,
+    ///     internal, in-place, stable,
+    ///     time complexity: O(n2),
+    ///     space complexity: O(1).
+    /// </summary>
+    /// <param name="array">Array to sort.</param>
+    /// <param name="comparer">Compares elements.</param>
+    public void Sort(T[] array, IComparer<T> comparer)
+    {
+        int index = 0;
+
+        while (index < array.Length)
+        {
+            if (index == 0 || comparer.Compare(array[index], array[index - 1]) >= 0)
+            {
+                index++;
+            }
+            else
+            {
+                Swap(array, index, index - 1);
+                index--;
+            }
+        }
+    }
+
+    public void Swap(T[] array, int index1, int index2)
+    {
+        (array[index1], array[index2]) = (array[index2], array[index1]);
+    }
+}
diff --git a/README.md b/README.md
index c9fd190e..198d2bd7 100644
--- a/README.md
+++ b/README.md
@@ -124,6 +124,7 @@ find more than one implementation for the same objective but using different alg
       * [Comb Sort](./Algorithms/Sorters/Comparison/CombSorter.cs)
       * [Cycle Sort](./Algorithms/Sorters/Comparison/CycleSorter.cs)
       * [Exchange Sort](./Algorithms/Sorters/Comparison/ExchangeSorter.cs)
+      * [Gnome Sort](./Algorithms/Sorters/Comparison/GnomeSorter.cs)
       * [Heap Sort](./Algorithms/Sorters/Comparison/HeapSorter.cs)
       * [Insertion Sort](./Algorithms/Sorters/Comparison/InsertionSorter.cs)
       * [Merge Sort](./Algorithms/Sorters/Comparison/MergeSorter.cs)