From 455ef1ba541ba5c1447469066109708db39063c3 Mon Sep 17 00:00:00 2001
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 =?UTF-8?q?=D0=B0=D0=BD?= <roman.pytkov@mail.ru>
Date: Sat, 26 Jul 2025 22:44:47 +0300
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---
 Chapter4_QuickSort/Program.cs   |  7 +++++++
 Chapter4_QuickSort/QuickSort.cs | 37 +++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 Chapter4_QuickSort/QuickSort.cs

diff --git a/Chapter4_QuickSort/Program.cs b/Chapter4_QuickSort/Program.cs
index 65b9f80..9afbc75 100644
--- a/Chapter4_QuickSort/Program.cs
+++ b/Chapter4_QuickSort/Program.cs
@@ -17,3 +17,10 @@ int target = 42;
 int index = Task4_4.BinSearch(sortedArr, target, 0, sortedArr.Length - 1);
 Console.WriteLine($"4.4. Индекс числа {target} в массиве: {index}");
 
+// Пример использования QuickSort
+List<int> unsorted = new() { 5, 2, 9, 1, 7, 3 };
+Console.WriteLine("Быстрая сортировка");
+Console.WriteLine($"Неотсортированный список: {string.Join(", ", unsorted)}");
+var sorted = QuickSort.Sort(unsorted, Comparer<int>.Default);
+Console.WriteLine($"Отсортированный список: {string.Join(", ", sorted)}");
+
diff --git a/Chapter4_QuickSort/QuickSort.cs b/Chapter4_QuickSort/QuickSort.cs
new file mode 100644
index 0000000..ecac3be
--- /dev/null
+++ b/Chapter4_QuickSort/QuickSort.cs
@@ -0,0 +1,37 @@
+static class QuickSort
+{
+    private static readonly Random _rnd = Random.Shared;
+
+    public static List<T> Sort<T>(List<T> source, Comparer<T> comparer)
+    {
+        if (source.Count < 2)
+            return source;
+
+        var referenceIndex = _rnd.Next(source.Count);
+        var reference = source[referenceIndex];
+        var less = new List<T>();
+        var equal = new List<T>();
+        var more = new List<T>();
+
+        for (var i = 0; i < source.Count; i++)
+        {
+            var value = source[i];
+            if (comparer.Compare(value, reference) < 0)
+                less.Add(value);
+            else if (comparer.Compare(value, reference) > 0)
+                more.Add(value);
+            else if (comparer.Compare(value, reference) == 0)
+                equal.Add(value);
+        }
+        less = Sort(less, comparer);
+        more = Sort(more, comparer);
+        var index = 0;
+        foreach (var item in less)
+            source[index++] = item;
+        foreach (var item in equal)
+            source[index++] = item;
+        foreach (var item in more)
+            source[index++] = item;
+        return source;
+    }
+}
\ No newline at end of file