225. Implement Stack using Queues

225. Implement Stack using Queues/225. Implement Stack using Queues.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+        <RootNamespace>_225._Implement_Stack_using_Queues</RootNamespace>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+</Project>

225. Implement Stack using Queues/MyStack.cs

@@ -0,0 +1,50 @@
+namespace _225._Implement_Stack_using_Queues;
+
+public class MyStack
+{
+    private Queue<int> _queue = new Queue<int>(256);
+    private int? _lastNum = null;
+
+    public MyStack()
+    {
+    }
+
+    public void Push(int x)
+    {
+        if (_lastNum == null)
+        {
+            _lastNum = x;
+            return;
+        }
+
+        int count = _queue.Count;
+        _queue.Enqueue(_lastNum.Value);
+        _lastNum = x;
+        while (count-- > 0)
+            _queue.Enqueue(_queue.Dequeue());
+    }
+
+    public int Pop()
+    {
+        if (_lastNum != null)
+        {
+            int res = _lastNum.Value;
+            _lastNum = null;
+            return res;
+        }
+
+        return _queue.Dequeue();
+    }
+
+    public int Top()
+    {
+        if (_lastNum != null)
+            return _lastNum.Value;
+        return _queue.Peek();
+    }
+
+    public bool Empty()
+    {
+        return _lastNum == null && _queue.Count == 0;
+    }
+}

225. Implement Stack using Queues/Program.cs

@@ -0,0 +1,3 @@
+// See https://aka.ms/new-console-template for more information
+
+Console.WriteLine("Hello, World!");

Leetcode.sln

@@ -163,6 +163,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "8. String to Integer (atoi)
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "15. 3Sum", "15. 3Sum\15. 3Sum.csproj", "{4FAFB0B1-A240-44B9-8305-3CA7FED8AE3C}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "225. Implement Stack using Queues", "225. Implement Stack using Queues\225. Implement Stack using Queues.csproj", "{4DF0467F-C3C9-4F92-9EE7-D21AD30F559D}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -489,6 +491,10 @@ Global
 		{4FAFB0B1-A240-44B9-8305-3CA7FED8AE3C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{4FAFB0B1-A240-44B9-8305-3CA7FED8AE3C}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{4FAFB0B1-A240-44B9-8305-3CA7FED8AE3C}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4DF0467F-C3C9-4F92-9EE7-D21AD30F559D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4DF0467F-C3C9-4F92-9EE7-D21AD30F559D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4DF0467F-C3C9-4F92-9EE7-D21AD30F559D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4DF0467F-C3C9-4F92-9EE7-D21AD30F559D}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE