[#3005] feat(leetcode): init project, add C# solution

problems/3005-count_elements_with_maximum_frequency/3005-count_elements_with_maximum_frequency.sln

@@ -0,0 +1,30 @@
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.2.0
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp", "csharp\csharp.csproj", "{CF022C7B-CAF3-706D-67E1-FB93518229B7}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestProject", "test\TestProject.csproj", "{C670389A-9CE7-B456-51E5-A79D56E199CF}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{CF022C7B-CAF3-706D-67E1-FB93518229B7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{CF022C7B-CAF3-706D-67E1-FB93518229B7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{CF022C7B-CAF3-706D-67E1-FB93518229B7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{CF022C7B-CAF3-706D-67E1-FB93518229B7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C670389A-9CE7-B456-51E5-A79D56E199CF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C670389A-9CE7-B456-51E5-A79D56E199CF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C670389A-9CE7-B456-51E5-A79D56E199CF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C670389A-9CE7-B456-51E5-A79D56E199CF}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {50409315-93FE-4BEF-BAEC-4B70A05B634A}
+	EndGlobalSection
+EndGlobal

problems/3005-count_elements_with_maximum_frequency/README.md

@@ -0,0 +1,91 @@
+# [3005] Count_elements_with_maximum_frequency
+
+## 題目資訊
+- **難度**: Easy
+- **標籤**: 
+- **題目連結**: https://leetcode.com/problems/count_elements_with_maximum_frequency/
+- **練習日期**: 2025-09-22
+- **目標複雜度**: 時間 O(?)、空間 O(?)
+
+## 題目描述
+> 在這裡貼上題目的完整描述（或重點）
+
+## 先備條件與限制
+- 輸入限制：n ∈ [?, ?]、值域 ∈ [?, ?]
+- 回傳/輸出格式：...
+- 其他：是否允許排序/就地修改
+
+## 解題思路
+
+### 初步分析
+- 類型：雙指針 / 滑動視窗 / 排序 / DP / 貪心 / 圖論 ...
+- 關鍵觀察：
+- 複雜度目標理由：
+
+### 解法比較
+1. 解法A（基準/暴力）：
+   - 思路：
+   - 正確性：
+   - 複雜度：O(?) / O(?)
+2. 解法B（優化）：
+   - 思路：
+   - 正確性：
+   - 複雜度：O(?) / O(?)
+
+### 乾跑（Dry Run）
+- 範例：...
+
+## 實作細節與 API 設計
+
+### C# 方法簽名（示意）
+```csharp
+public class Solution {
+    // TODO: 根據題意調整簽名
+    public int Solve(int[] nums) {
+        return 0;
+    }
+}
+```
+
+### Go 方法簽名（示意）
+```go
+func solve(nums []int) int {
+    return 0
+}
+```
+
+### 常見陷阱
+- 邊界：空/單一/極值/全相等
+- 去重：排序後跳重複、集合
+- 溢位：使用 64-bit
+
+## 測試案例
+
+### 範例輸入輸出
+```
+Input: ...
+Output: ...
+Explanation: ...
+```
+
+### 邊界清單
+- [ ] 空陣列/空字串
+- [ ] 單一元素 / 全相同
+- [ ] 含負數/0/大數
+- [ ] 去重
+- [ ] 大資料壓力
+
+## 複雜度分析
+- 最壞：時間 O(?)、空間 O(?)
+
+## 相關題目 / Follow-up
+- 
+
+## 學習筆記
+- 今天學到：
+- 卡住與修正：
+- 待優化：
+
+---
+**總結**：這題的核心在於 ______，適合練習 ______。
+

problems/3005-count_elements_with_maximum_frequency/csharp/Program.cs

@@ -0,0 +1,52 @@
+// LeetCode 3005: Count_elements_with_maximum_frequency
+// 難度: Easy
+// 日期: 2025-09-22
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public class Solution {
+    public int MaxFrequencyElements(int[] nums)
+    {
+        Dictionary<int, int> frequencyMap = new Dictionary<int, int>();
+
+        // put nums into dictionary map
+        foreach (var num in nums)
+        {
+            if (!frequencyMap.ContainsKey(num))
+            {
+                frequencyMap.Add(num, 0);
+            }
+            frequencyMap[num]++;
+        }
+
+        // find most frequency nums
+        int maxFrequency = 0;
+        if (frequencyMap.Count != 0)
+        {
+            maxFrequency = frequencyMap.Values.Max();
+        }
+
+        // count if have same max frequency nus
+        int count = 0;
+        foreach (var dic in frequencyMap)
+        {
+            if (dic.Value == maxFrequency)
+            {
+                count += maxFrequency;
+            }
+        }
+
+        return count;
+    }
+}
+
+public class Program {
+    public static void Main() {
+        var s = new Solution();
+        // TODO: 可加入簡單輸入/輸出測試
+        Console.WriteLine("Hello LeetCode 3005!");
+    }
+}
+

problems/3005-count_elements_with_maximum_frequency/csharp/csharp.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+</Project>
+

problems/3005-count_elements_with_maximum_frequency/go/main.go

@@ -0,0 +1,18 @@
+// LeetCode 3005: Count_elements_with_maximum_frequency
+// 難度: Easy
+// 日期: 2025-09-22
+
+package main
+
+import "fmt"
+
+// TODO: 根據題意調整簽名
+func solve(nums []int) int {
+    return 0
+}
+
+func main() {
+    fmt.Printf("Hello LeetCode 3005!\n")
+    // TODO: 可加入簡單測試
+}
+

problems/3005-count_elements_with_maximum_frequency/test/SolutionTests.cs

@@ -0,0 +1,24 @@
+// LeetCode 3005 單元測試（xUnit）
+
+using Xunit;
+
+public class SolutionTests {
+    private readonly Solution _s = new Solution();
+
+    [Fact]
+    public void Example1() {
+        // TODO: Arrange
+        // var input = new int[] { };
+        // var expected = 0;
+        // Act
+        // var got = _s.Solve(input);
+        // Assert.Equal(expected, got);
+        Assert.True(true);
+    }
+
+    [Fact]
+    public void EdgeCases() {
+        Assert.True(true);
+    }
+}
+

problems/3005-count_elements_with_maximum_frequency/test/TestProject.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
+    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="../csharp/csharp.csproj" />
+  </ItemGroup>
+</Project>
+

problems/3005-count_elements_with_maximum_frequency/test/main_test.go

@@ -0,0 +1,12 @@
+// LeetCode 3005 單元測試（Go testing）
+package main
+
+import "testing"
+
+func TestExample(t *testing.T) {
+    // TODO: input := []int{}
+    // got := solve(input)
+    // want := 0
+    // if got != want { t.Fatalf("want %v got %v", want, got) }
+}
+