[#0166 ] feat(leetcode): add README, unit test and C# solution

[#0166 ] feat(leetcode): init project
remove: legacy solutions
2025-09-24 11:18:08 +08:00 · 2025-09-24 09:35:00 +08:00 · 2025-09-24 09:34:13 +08:00 · 2025-09-23 11:02:46 +08:00 · 2025-09-23 10:59:18 +08:00 · 2025-09-22 13:51:44 +08:00
62 changed files with 918 additions and 1130 deletions
--- a/largestGoodInteger/C#/C#.sln
+++ b/largestGoodInteger/C#/C#.sln
@@ -1,24 +0,0 @@
-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}") = "largestGoodInteger", "largestGoodInteger.csproj", "{DF73131C-3A52-FFDC-7C0C-19190AA3E331}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{DF73131C-3A52-FFDC-7C0C-19190AA3E331}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{DF73131C-3A52-FFDC-7C0C-19190AA3E331}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{DF73131C-3A52-FFDC-7C0C-19190AA3E331}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{DF73131C-3A52-FFDC-7C0C-19190AA3E331}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {E9F3A871-90C4-4B8E-81E2-B0AF873694BF}
-	EndGlobalSection
-EndGlobal
--- a/largestGoodInteger/C#/Program.cs
+++ b/largestGoodInteger/C#/Program.cs
@@ -1,63 +0,0 @@
-public class Solution {
-    public string LargestGoodInteger(string num)
-    {
-        // var count = 0;
-        // char lastNum = 'a';
-        // var numList = new List<int>();
-        // for (var i = 0; i < num.Length; i++)
-        // {
-        //     if (num[i] == lastNum)
-        //     {
-        //         count++;
-        //         if (count == 3)
-        //         {
-        //             numList.Add(int.Parse(num[i].ToString()));
-        //         }
-        //     }
-        //     else
-        //     {
-        //         count = 1;
-        //     }
-
-        //     lastNum = num[i];
-        // }
-
-        // if (numList.Count == 0)
-        // {
-        //     return "";
-        // }
-        // else
-        // {
-        //     var a = numList.Max().ToString();
-        //     return $"{a}{a}{a}";
-        // }
-
-        string max = "";
-
-        for (int i = 0; i < num.Length - 2; i++)
-        {
-            if (num[i] == num[i + 1] && num[i] == num[i + 2])
-            {
-                string current = $"{num[i]}{num[i]}{num[i]}";
-
-                if (max == "") max = current;
-                else
-                {
-                    if (int.Parse(current) > int.Parse(max))
-                        max = current;
-                }
-            }
-        }
-        return max;
-    }
-}
-
-class program
-{
-    static void Main()
-    {
-        var solution = new Solution();
-
-        Console.WriteLine(solution.LargestGoodInteger("6777133339"));
-    }
-}
--- a/largestGoodInteger/GO/main.go
+++ b/largestGoodInteger/GO/main.go
@@ -1,23 +0,0 @@
-package main
-
-import "fmt"
-
-func LargestGoodInteger(num string) string {
-	max := ""
-
-	for i := 0; i < len(num)-2; i++ {
-		if num[i] == num[i+1] && num[i] == num[i+2] {
-			current := string([]byte{num[i], num[i], num[i]})
-
-			if current > max {
-				max = current
-			}
-		}
-	}
-
-	return max
-}
-
-func main() {
-	fmt.Println(LargestGoodInteger("7636669283"))
-}
--- a/ProductQueries/C#/2438
+++ b/ProductQueries/C#/2438
@@ -1,24 +0,0 @@
-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}") = "ProductQueries", "C#\ProductQueries.csproj", "{412F89C4-B1BF-D819-298B-9C873A098742}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{412F89C4-B1BF-D819-298B-9C873A098742}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{412F89C4-B1BF-D819-298B-9C873A098742}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{412F89C4-B1BF-D819-298B-9C873A098742}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{412F89C4-B1BF-D819-298B-9C873A098742}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {BDF3A5A3-29B8-4169-8A46-A13A7DE900D8}
-	EndGlobalSection
-EndGlobal
--- a/ProductQueries/C#/Program.cs
+++ b/ProductQueries/C#/Program.cs
@@ -1,69 +0,0 @@
-using System;
-
-public class Solution
-{
-    public int[] ProductQueries(int n, int[][] queries)
-    {
-        // 1. n => calculate in powers of 2
-        // 2. get number array without 0
-        var powers = CalPower(n);
-
-        return CalQueries(powers, queries);
-
-    }
-
-    private int[] CalPower(int n)
-    {
-        var result = new List<int>();
-
-        while (n > 0)
-        {
-            var num = n % 2;
-            result.Add(num);
-            n /= 2;
-        }
-
-        var newResult = new List<int>();
-        for (var i = 0; i < result.Count; i++)
-        {
-            if (result[i] != 0)
-            {
-                var ans = (int)Math.Pow(2, i);
-                newResult.Add(ans);
-            }
-        }
-        return newResult.ToArray();
-    }
-
-    private int[] CalQueries(int[] powers, int[][] queries)
-    {
-        const int MOD = 1000000007;
-        var result = new List<int>();
-
-        foreach (var query in queries)
-        {
-            long count = 1;
-            for (var i = query[0]; i <= query[1]; i++)
-            {
-                count = (count * powers[i]) % MOD;
-            }
-            result.Add(count);
-        }
-
-        return result.ToArray();
-    }
-}
-
-class Program
-{
-    static void Main()
-    {
-        var Solution = new Solution();
-
-        var ans = Solution.ProductQueries(15, [[0, 1], [2, 2], [0, 3]]);
-        Console.WriteLine(string.Join(", ", ans));
-
-        ans = Solution.ProductQueries(919, [[5,5],[4,4],[0,1],[1,5],[4,6],[6,6],[5,6],[0,3],[5,5],[5,6],[1,2],[3,5],[3,6],[5,5],[4,4],[1,1],[2,4],[4,5],[4,4],[5,6],[0,4],[3,3],[0,4],[0,5],[4,4],[5,5],[4,6],[4,5],[0,4],[6,6],[6,6],[6,6],[2,2],[0,5],[1,4],[0,3],[2,4],[5,5],[6,6],[2,2],[2,3],[5,5],[0,6],[3,3],[6,6],[4,4],[0,0],[0,2],[6,6],[6,6],[3,6],[0,4],[6,6],[2,2],[4,6]]);
-         Console.WriteLine(string.Join(", ", ans));
-    }
-}
--- a/ProductQueries/description.md
+++ b/ProductQueries/description.md
@@ -1,5 +0,0 @@
-Given a positive integer n, there exists a 0-indexed array called powers, composed of the minimum number of powers of 2 that sum to n. The array is sorted in non-decreasing order, and there is only one way to form the array.
-
-You are also given a 0-indexed 2D integer array queries, where queries[i] = [lefti, righti]. Each queries[i] represents a query where you have to find the product of all powers[j] with lefti <= j <= righti.
-
-Return an array answers, equal in length to queries, where answers[i] is the answer to the ith query. Since the answer to the ith query may be too large, each answers[i] should be returned modulo 109 + 7.
--- a/numberOfWays/C#/C#.sln
+++ b/numberOfWays/C#/C#.sln
@@ -1,24 +0,0 @@
-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}") = "numberOfWays", "numberOfWays.csproj", "{1E81E272-AF2C-9CB4-F90B-0AAC263D10DC}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{1E81E272-AF2C-9CB4-F90B-0AAC263D10DC}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{1E81E272-AF2C-9CB4-F90B-0AAC263D10DC}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{1E81E272-AF2C-9CB4-F90B-0AAC263D10DC}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{1E81E272-AF2C-9CB4-F90B-0AAC263D10DC}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {AD18FC84-E2FB-4382-96DF-8AE7E50C1401}
-	EndGlobalSection
-EndGlobal
--- a/numberOfWays/C#/Program.cs
+++ b/numberOfWays/C#/Program.cs
@@ -1,48 +0,0 @@
-// knapsack problem
-public class Solution
-{
-    public int NumberOfWays(int n, int x)
-    {
-        const int MOD = 1_000_000_007;
-        // list all the powers which smaller than n
-        var powers = new List<int>();
-        var num = 1;
-
-        while (true)
-        {
-            int pow = (int)Math.Pow(num, x);
-            if (pow > n)
-                break;
-            powers.Add(pow);
-            num++;
-        }
-
-        // dynamic programming
-        var dp = new int[n + 1];
-        dp[0] = 1;
-
-        foreach (var power in powers)
-        {
-            for (var i = n; i >= power; i--)
-            {
-                dp[i] = (dp[i] + dp[i - power]) % MOD;
-            }
-        }
-
-        return dp[n];
-
-    }
-
-}
-
-class Program
-{
-    static void Main()
-    {
-        var solution = new Solution();
-
-        Console.WriteLine(solution.NumberOfWays(4, 1));
-        Console.WriteLine(solution.NumberOfWays(100, 3));
-
-    }
-}
--- a/areaOfMaxDiagonal/C#/Program.cs
+++ b/areaOfMaxDiagonal/C#/Program.cs
@@ -1,38 +0,0 @@
-public class Solution
-{
-    public int AreaOfMaxDiagonal(int[][] dimensions)
-    {
-        int max = 0;
-        int maxArea = 0;
-
-        foreach (var dimension in dimensions)
-        {
-            var dimensionSqrt = dimension[0] * dimension[0] + dimension[1] * dimension[1];
-            var area = dimension[0] * dimension[1];
-            if (dimensionSqrt > max)
-            {
-                max = dimensionSqrt;
-                maxArea = area;
-            }
-            else if (dimensionSqrt == max)
-            {
-                maxArea = Math.Max(maxArea, area);
-            }
-        }
-        return maxArea;
-    }
-}
-
-public class Program
-{
-    public static void Main()
-    {
-        var Solution = new Solution();
-
-        var dimensions = new int[][] { [6,5],[8,6],[2,10],[8,1],[9,2],[3,5],[3,5]};
-
-        var result = Solution.AreaOfMaxDiagonal(dimensions);
-        Console.WriteLine(result);
-    }
-}
-
--- a/areaOfMaxDiagonal/C#/areaOfMaxDiagonal.csproj
+++ b/areaOfMaxDiagonal/C#/areaOfMaxDiagonal.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/areaOfMaxDiagonal/GO/main.go
+++ b/areaOfMaxDiagonal/GO/main.go
@@ -1,27 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"math"
-)
-
-func areaOfMaxDiagonal(dimensions [][]int) int{
-	maxDiagonal := 0
-	maxArea := 0
-
-	for _, dimension := range dimensions{
-		l := dimension[0]
-		w := dimension[1]
-		diagonalSquare := l * l + w * w
-		area := l * w
-
-		if diagonalSquare > maxDiagonal{
-			maxDiagonal = diagonalSquare
-			maxArea = area
-		}else if diagonalSquare == maxDiagonal{
-			maxArea = int(math.Max(float64(maxArea), float64(area)))
-		}
-	}
-
-	return maxArea
-}
--- a/minimumArea/C#/C#.sln
+++ b/minimumArea/C#/C#.sln
@@ -1,24 +0,0 @@
-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}") = "MinimumArea", "MinimumArea.csproj", "{61A8B87F-638B-4246-13C4-CC226CFBBEA5}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{61A8B87F-638B-4246-13C4-CC226CFBBEA5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{61A8B87F-638B-4246-13C4-CC226CFBBEA5}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{61A8B87F-638B-4246-13C4-CC226CFBBEA5}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{61A8B87F-638B-4246-13C4-CC226CFBBEA5}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {C6FDF6F7-60CD-4B35-B619-6F79B7243CA7}
-	EndGlobalSection
-EndGlobal
--- a/minimumArea/C#/MinimumArea.csproj
+++ b/minimumArea/C#/MinimumArea.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/minimumArea/C#/Program.cs
+++ b/minimumArea/C#/Program.cs
@@ -1,28 +0,0 @@
-public class Solution {
-    public int MinimumArea(int[][] grid)
-    {
-        var x = grid[0].Length;
-        var y = grid.Length;
-
-        int min_x = x;
-        int max_x = 0;
-        int min_y = y;
-        int max_y = 0;
-
-        for (var i = 0; i < x; i++)
-        {
-            for (var j = 0; j < y; j++)
-            {
-                if (grid[j][i])
-                {
-                    min_x = Math.Min(min_x, i);
-                    max_x = Math.Max(max_x, i);
-                    min_y = Math.Min(min_y, j);
-                    max_y = Math.Max(max_y, j);
-                }
-            }
-        }
-
-        return (max_x - min_x + 1) * (max_y - min_y + 1);
-    }
-}
--- a/minimumArea/Go/main.go
+++ b/minimumArea/Go/main.go
@@ -1,40 +0,0 @@
-package main
-
-import "fmt"
-
-func minimumArea(grid [][]int) int {
-    row := len(grid)
-	col := len(grid[0])
-
-	min_x := col
-	max_x := 0
-	min_y := row
-	max_y := 0
-	
-	for i:=0; i<row; i++{
-		for j:=0; j<col; j++{
-			if grid[i][j] == 1{
-				min_x = Min(min_x, j)
-				max_x = Max(max_x, j)
-				min_y = Min(min_y, i)
-				max_y = Max(max_y, i)
-			}
-		}
-	}
-
-	return (max_x-min_x+1) * (max_y-min_y+1)
-}
-
-func Min(a, b int)int{
-	if a < b {
-		return a
-	}
-	return b
-}
-
-func Max(a, b int)int{
-	if a > b{
-		return a
-	}
-	return b
-}
--- a/isPowerOfThree/C#/Program.cs
+++ b/isPowerOfThree/C#/Program.cs
@@ -1,21 +0,0 @@
-public class Solution {
-    public bool IsPowerOfThree(int n) {
-        if(n <= 0)
-            return false;
-        if(n == 1)
-            return true;
-        if(n % 3 != 0)
-            return false;
-        return IsPowerOfThree(n/3);
-    }
-}
-
-class program{
-    static void Main(){
-        var Solution = new Solution();
-
-        Console.WriteLine(Solution.IsPowerOfThree(9));
-        Console.WriteLine(Solution.IsPowerOfThree(0));
-        Console.WriteLine(Solution.IsPowerOfThree(-1));
-    }
-}
--- a/isPowerOfThree/C#/isPowerOfThree.csproj
+++ b/isPowerOfThree/C#/isPowerOfThree.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/isPowerOfThree/description.md
+++ b/isPowerOfThree/description.md
@@ -1,22 +0,0 @@
-Given an integer n, return true if it is a power of three. Otherwise, return false.
-
-An integer n is a power of three, if there exists an integer x such that n == 3x.
-
- 
-
-Example 1:
-
-Input: n = 27
-Output: true
-Explanation: 27 = 33
-Example 2:
-
-Input: n = 0
-Output: false
-Explanation: There is no x where 3x = 0.
-Example 3:
-
-Input: n = -1
-Output: false
-Explanation: There is no x where 3x = (-1).
- 
--- a/isPowerOfThree/go/app.go
+++ b/isPowerOfThree/go/app.go
@@ -1,26 +0,0 @@
-package main
-
-import "fmt"
-
-type Solution struct{}
-
-func (s Solution) IsPowerOfThree(n int) bool{
-	if n <= 0{
-		return false
-	}
-	if n == 1{
-		return true
-	}
-	if n % 3 != 0{
-		return false
-	}
-	return s.IsPowerOfThree(n/3)
-}
-
-func main(){
-	solution := Solution{}
-
-	fmt.Println(solution.IsPowerOfThree(27))
-	fmt.Println(solution.IsPowerOfThree(0))
-	fmt.Println(solution.IsPowerOfThree(-1))
-}
--- a/MaxCollectedFruits/C#/MaxCollectedFruits.csproj
+++ b/MaxCollectedFruits/C#/MaxCollectedFruits.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/MaxCollectedFruits/C#/MaxCollectedFruits.sln
+++ b/MaxCollectedFruits/C#/MaxCollectedFruits.sln
@@ -1,24 +0,0 @@
-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}") = "MaxCollectedFruits", "MaxCollectedFruits.csproj", "{AA67CF61-67B3-7229-E3F9-D471B0EF4EDE}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{AA67CF61-67B3-7229-E3F9-D471B0EF4EDE}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{AA67CF61-67B3-7229-E3F9-D471B0EF4EDE}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{AA67CF61-67B3-7229-E3F9-D471B0EF4EDE}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{AA67CF61-67B3-7229-E3F9-D471B0EF4EDE}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {B9D47F51-61C3-4A24-890A-01C9AC85EC93}
-	EndGlobalSection
-EndGlobal
--- a/MaxCollectedFruits/C#/Program.cs
+++ b/MaxCollectedFruits/C#/Program.cs
@@ -1,67 +0,0 @@
-public class Solution
-{
-    public int MaxCollectedFruits(int[][] fruits)
-    {
-        int n = fruits.Length;
-        int ans = 0;
-        for (int i = 0; i < n; ++i) ans += fruits[i][i];
-
-        int dp()
-        {
-            int[] prev = Enumerable.Repeat(int.MinValue, n).ToArray();
-            int[] curr = new int[n];
-            prev[n - 1] = fruits[0][n - 1];
-            for (int i = 1; i < n - 1; ++i)
-            {
-                Array.Fill(curr, int.MinValue);
-                for (int j = Math.Max(n - 1 - i, i + 1); j < n; ++j)
-                {
-                    int best = prev[j];
-                    if (j - 1 >= 0)
-                    {
-                        best = Math.Max(best, prev[j - 1]);
-                    }
-                    if (j + 1 < n)
-                    {
-                        best = Math.Max(best, prev[j + 1]);
-                    }
-                    curr[j] = best + fruits[i][j];
-                }
-                var temp = prev;
-                prev = curr;
-                curr = temp;
-            }
-            return prev[n - 1];
-        }
-
-        ans += dp();
-
-        for (int i = 0; i < n; ++i)
-        {
-            for (int j = 0; j < i; ++j)
-            {
-                var temp = fruits[j][i];
-                fruits[j][i] = fruits[i][j];
-                fruits[i][j] = temp;
-            }
-        }
-
-        ans += dp();
-        return ans;
-    }
-
-
-}
-
-
-class Program
-{
-    static void Main()
-    {
-        var Solution = new Solution();
-
-        var fruits = new int[][] { [1,2,3,4],[5,6,8,7],[9,10,11,12],[13,14,15,16]};
-
-        Console.WriteLine(Solution.MaxCollectedFruits(fruits));
-    }
-}
--- a/SortMatrix/C#/C#.sln
+++ b/SortMatrix/C#/C#.sln
@@ -1,24 +0,0 @@
-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}") = "SortMatrix", "SortMatrix.csproj", "{60318F94-4F41-A4B8-C189-A8135ECCECCB}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{60318F94-4F41-A4B8-C189-A8135ECCECCB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{60318F94-4F41-A4B8-C189-A8135ECCECCB}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{60318F94-4F41-A4B8-C189-A8135ECCECCB}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{60318F94-4F41-A4B8-C189-A8135ECCECCB}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {9F59D1F6-D9F3-492C-BC39-A5771AF22B36}
-	EndGlobalSection
-EndGlobal
--- a/SortMatrix/C#/Program.cs
+++ b/SortMatrix/C#/Program.cs
@@ -1,115 +0,0 @@
-public class Solution
-{
-    public int[][] SortMatrix(int[][] grid)
-    {
-        // 左下
-        var leftDiagonals = new Dictionary<int, List<int>>();
-        for (var i = 0; i < grid.Length; i++)
-        {
-            // total -> 2n + 1 way
-            for (var j = 0; j <= i; j++)
-            {
-                int diagonal = i - j;
-                if (!leftDiagonals.ContainsKey(diagonal))
-                {
-                    leftDiagonals[diagonal] = new List<int>();
-                }
-                leftDiagonals[diagonal].Add(grid[i][j]);
-            }
-        }
-
-        // 右上
-        var rightDiagonals = new Dictionary<int, List<int>>();
-        for (var i = 0; i < grid.Length; i++)
-        {
-            for (var j = i; j < grid.Length; j++)
-            {
-                int diagonal = j - i;
-                if (!rightDiagonals.ContainsKey(diagonal))
-                {
-                    rightDiagonals[diagonal] = new List<int>();
-                }
-                rightDiagonals[diagonal].Add(grid[i][j]);
-            }
-        }
-
-        foreach (var diagonal in leftDiagonals.Values)
-        {
-            diagonal.Sort((a, b) => b.CompareTo(a));
-        }
-
-        foreach (var diagonal in rightDiagonals.Values)
-        {
-            diagonal.Sort((a, b) => a.CompareTo(b));
-        }
-
-        for (var i = 0; i < grid.Length; i++)
-        {
-            for (var j = 0; j <= i; j++)
-            {
-                int diagonal = i - j;
-                grid[i][j] = leftDiagonals[diagonal][0];
-                leftDiagonals[diagonal].RemoveAt(0);
-            }
-
-            for (var j = i; j < grid.Length; j++)
-            {
-                if (i == j) continue;
-                int diagonal = j - i;
-                grid[i][j] = rightDiagonals[diagonal][0];
-                rightDiagonals[diagonal].RemoveAt(0);
-            }
-        }
-        return grid;
-    }
-}
-
-public class Solution2 {
-    public int[][] SortMatrix(int[][] grid) {
-        int n = grid.Length;
-
-        for (int i = 0; i < n; i++) {
-            List<int> tmp = new List<int>();
-            for (int j = 0; i + j < n; j++) {
-                tmp.Add(grid[i + j][j]);
-            }
-            tmp.Sort((a, b) => b.CompareTo(a));
-            for (int j = 0; i + j < n; j++) {
-                grid[i + j][j] = tmp[j];
-            }
-        }
-
-        for (int j = 1; j < n; j++) {
-            List<int> tmp = new List<int>();
-            for (int i = 0; j + i < n; i++) {
-                tmp.Add(grid[i][j + i]);
-            }
-            tmp.Sort();
-            for (int i = 0; j + i < n; i++) {
-                grid[i][j + i] = tmp[i];
-            }
-        }
-
-        return grid;
-    }
-}
-
-class Program
-{
-    static void Main()
-    {
-        var Solution = new Solution();
-
-        var gird = new int[][] { [1, 7, 3], [9, 8, 2], [4, 5, 6] };
-        var result = Solution.SortMatrix(gird);
-
-        for (int i = 0; i < result.Length; i++)
-        {
-            for (int j = 0; j < result[i].Length; j++)
-            {
-                Console.Write(result[i][j] + " ");
-            }
-            Console.WriteLine();
-        }
-    }
-}
--- a/SortMatrix/C#/SortMatrix.csproj
+++ b/SortMatrix/C#/SortMatrix.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/FindDiagonalOrder/C#/C#.sln
+++ b/FindDiagonalOrder/C#/C#.sln
@@ -1,24 +0,0 @@
-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}") = "FindDiagonalOrder", "FindDiagonalOrder.csproj", "{B3151728-C057-4305-DD4C-9A2AFBFC189A}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{B3151728-C057-4305-DD4C-9A2AFBFC189A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{B3151728-C057-4305-DD4C-9A2AFBFC189A}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{B3151728-C057-4305-DD4C-9A2AFBFC189A}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{B3151728-C057-4305-DD4C-9A2AFBFC189A}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {DB56539A-6F32-4D28-B91F-BB1DCF46F4D0}
-	EndGlobalSection
-EndGlobal
--- a/FindDiagonalOrder/C#/FindDiagonalOrder.csproj
+++ b/FindDiagonalOrder/C#/FindDiagonalOrder.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/FindDiagonalOrder/C#/Program.cs
+++ b/FindDiagonalOrder/C#/Program.cs
@@ -1,61 +0,0 @@
-public class Solution {
-    public int[] FindDiagonalOrder(int[][] mat)
-    {
-        if (mat == null || mat.Length == 0 || mat[0].Length == 0)
-        {
-            return new int[0];
-        }
-
-        var m = mat.Length;
-        var n = mat[0].Length;
-
-        var diagonals = new Dictionary<int, List<int>>();
-
-        for (var i = 0; i < m; i++)
-        {
-            for (var j = 0; j < n; j++)
-            {
-                int diagonalIndex = i + j;
-                if (!diagonals.ContainsKey(diagonalIndex))
-                {
-                    diagonals[diagonalIndex] = new List<int>();
-                }
-                diagonals[diagonalIndex].Add(mat[i][j]);
-            }
-        }
-
-        var result = new List<int>();
-        foreach (var key in diagonals.Keys)
-        {
-            var diagonal = diagonals[key];
-            if (key % 2 == 0)
-            {
-                result.AddRange(diagonal);
-            }
-            else
-            {
-                diagonal.Reverse();
-                result.AddRange(diagonal);
-            }
-        }
-
-        return result.ToArray();
-    }
-}
-
-class Program
-{
-    static void Main()
-    {
-        var Solution = new Solution();
-
-        int[][] mat1 = new int[][]{
-            new int[]{1,2,3},
-            new int[]{4,5,6},
-            new int[]{7,8,9}
-        };
-
-        Console.WriteLine(string.Join(", ", Solution.FindDiagonalOrder(mat1)));
-
-    }
-}
--- a/FindDiagonalOrder/Go/main.go
+++ b/FindDiagonalOrder/Go/main.go
@@ -1,45 +0,0 @@
-package main
-
-import "fmt"
-
-func findDiagonalOrder(mat [][]int) []int {
-	if len(mat) == 0 || len(mat[0]) == 0{
-		return []int{}
-	}
-
-	m := len(mat)
-	n := len(mat[0])
-	
-	// maps
-	diagonals := make(map[int][]int)
-
-	for i:=0; i< m;i++{
-		for j:=0; j < n; j++{
-			index := i+j
-			diagonals[index] = append(diagonals[index], mat[i][j])
-		}
-	}
-
-	result := []int{}
-
-	for i:= 0; i< m+n-1; i++{
-		if i% 2 == 0{
-			reverse(diagonals[i])
-			result = append(result, diagonals[i]...)
-		}else{
-			result = append(result, diagonals[i]...)
-		}
-	}
-
-	return result
-}
-
-func reverse(slice []int){
-	left, right :=0, len(slice)-1
-
-	for left < right{
-		slice[left], slice[right] = slice[right], slice[left]
-		left++
-		right--
-	}
-}
--- a/FindDiagonalOrder/solution.md
+++ b/FindDiagonalOrder/solution.md
@@ -1,7 +0,0 @@
-1. 觀察矩陣對角線模式
-   1. (0,0) -> 1 -> i+j = 0
-   2. (1, 0), (0, 1) -> 2 -> i+j = 1
-   3. (2, 0), (1, 1), (0, 2) -> 3 -> i+j = 2
-2. how to deal with diagonal sorting?
-   1. while (i+j) % 2 == 1 
-   2. while (i+j) % 2 == 0 reversed
--- a/soupServings/C#/C#.sln
+++ b/soupServings/C#/C#.sln
@@ -1,24 +0,0 @@
-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}") = "soupServings", "soupServings.csproj", "{6D960F00-6A53-6E19-86A1-4BF3D1CD764F}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{6D960F00-6A53-6E19-86A1-4BF3D1CD764F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{6D960F00-6A53-6E19-86A1-4BF3D1CD764F}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{6D960F00-6A53-6E19-86A1-4BF3D1CD764F}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{6D960F00-6A53-6E19-86A1-4BF3D1CD764F}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {11CC27B7-C17E-4820-8A68-ADD32A2B37F8}
-	EndGlobalSection
-EndGlobal
--- a/soupServings/C#/Program.cs
+++ b/soupServings/C#/Program.cs
@@ -1,56 +0,0 @@
-using System;
-
-public class Solution
-{
-    private Dictionary<(int, int), double> dp = new Dictionary<(int, int), double>();
-    public double SoupServings(int n)
-    {
-        if (n > 5000)
-            return 1.0;
-
-        n = (n + 24) / 25;
-
-        // use dynamic programming
-        return Helper(n, n);
-    }
-
-    private double Helper(int a, int b)
-    {
-        if (a <= 0 && b <= 0)
-        {
-            return 0.5;
-        }
-        if (a <= 0)
-        {
-            return 1.0;
-        }
-        if (b <= 0)
-        {
-            return 0.0;
-        }
-        if (dp.ContainsKey((a, b)))
-        {
-            return dp[(a, b)];
-        }
-
-        double probability = 0.25 * (
-            Helper(a - 4, b) +
-            Helper(a - 3, b - 1) +
-            Helper(a - 2, b - 2) +
-            Helper(a - 1, b - 3)
-        );
-
-        dp[(a, b)] = probability;
-        return probability;
-    }
-}
-
-class Program
-{
-    static void Main()
-    {
-        var Solution = new Solution();
-        var ans = Solution.SoupServings(800);
-        Console.WriteLine(ans);
-    }
-}
--- a/soupServings/C#/soupServings.csproj
+++ b/soupServings/C#/soupServings.csproj
@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>
--- a/soupServings/Go/main.go
+++ b/soupServings/Go/main.go
@@ -1,52 +0,0 @@
-package main
-
-import ("fmt")
-
-type Solution struct{
-	dp map[[2]int]float64
-}
-
-func NewSolution() *Solution{
-	return &Solution{dp: make(map[[2]int]float64)}
-}
-
-func (s *Solution) SoupServings(n int)float64{
-	if n > 5000{
-		return 1.0
-	}
-
-	n = (n+24) /25
-
-	return s.helper(n, n)
-}
-
-func (s * Solution) helper(a, b int) float64 {
-	if a <= 0 && b <= 0{
-		return 0.5
-	}
-	if a <= 0{
-		return 1.0
-	}
-	if b <= 0{
-		return 0
-	}
-
-	if val, exist := s.dp[[2]int{a, b}]; exist{
-		return val
-	}
-
-	probability := 0.25 * (
-		s.helper(a-4, b) +
-		s.helper(a-3, b-1) +
-		s.helper(a-2, b-2) +
-		s.helper(a-1, b-3))
-
-	s.dp[[2]int {a, b}] = probability
-	return probability
-}
-
-func main(){
-	Solution := NewSolution()
-	ans := Solution.SoupServings(100)
-	fmt.Println(ans)
-}
--- a/soupServings/description.md
+++ b/soupServings/description.md
@@ -1,14 +0,0 @@
-You have two soups, A and B, each starting with n mL. On every turn, one of the following four serving operations is chosen at random, each with probability 0.25 independent of all previous turns:
-
-pour 100 mL from type A and 0 mL from type B
-pour 75 mL from type A and 25 mL from type B
-pour 50 mL from type A and 50 mL from type B
-pour 25 mL from type A and 75 mL from type B
-Note:
-
-There is no operation that pours 0 mL from A and 100 mL from B.
-The amounts from A and B are poured simultaneously during the turn.
-If an operation asks you to pour more than you have left of a soup, pour all that remains of that soup.
-The process stops immediately after any turn in which one of the soups is used up.
-
-Return the probability that A is used up before B, plus half the probability that both soups are used up in the same turn. Answers within 10-5 of the actual answer will be accepted.
--- a/logs/2025-09.md
+++ b/logs/2025-09.md
@@ -17,6 +17,7 @@
 |------|------|------|------|------|------|------|
 | 09/08 | Convert Integer To The Sum Of Two No Zero Integers | Easy | C# | 0.2hr | Done | |
 | 09/11 | Sort Vowels In A String | Medium | C# | 0.2hr | Done | |
+| 09/11 | [3227]Vowels Game In A String | Medium | C#, go | 0.1hr | Done | like easy |

 ### Week 3
 | 日期 | 題目 | 難度 | 語言 | 耗時 | 狀態 | 心得 |
@@ -26,18 +27,19 @@
 ### Week 4
 | 日期 | 題目 | 難度 | 語言 | 耗時 | 狀態 | 心得 |
 |------|------|------|------|------|------|------|
-| | | | | | | |
+| 09/22 | [3005]Count Elements With Maximum Frequency | Easy | C# | 0.3hr | Done | Dictionary Mapping |
+| 09/23| [0165]Compare Version Numbers | Medium | C# | 0.4hr | Done | String, Two Pointers |

 ## 📈 本月統計

 ### 完成情況
- **總練習天數**: 7 天
- **完成題數**: 7題
- **語言分布**: C# 7(題), Go 2(題)
- **難度分布**: Easy 2(題), Medium 4(題), Hard 1(題)
+- **總練習天數**: 9 天
+- **完成題數**: 9題
+- **語言分布**: C# 9(題), Go 2(題)
+- **難度分布**: Easy 3(題), Medium 5(題), Hard 1(題)

 ### 時間投入
- **總時間**: 3.9小時
+- **總時間**: 4.5小時
 - **平均每題**: 分鐘
 - **每日平均**: 分鐘

--- a/22
+++ b/22
@@ -0,0 +1,22 @@
+# Makefile - 安裝環境工具
+
+.PHONY: all update upgrade install setup check
+
+all: setup
+
+update:
+	sudo apt update
+
+upgrade:
+	sudo apt upgrade -y
+
+install:
+	sudo apt install -y dotnet-sdk-8.0 golang-go
+
+setup: update upgrade install check
+	@echo "✅ 開發環境安裝完成！"
+
+check:
+	@echo "=== 檢查安裝結果 ==="
+	@dotnet --version || echo "⚠️ dotnet 未安裝成功"
+	@go version || echo "⚠️ go 未安裝成功"
--- a/problems/0165-compare-version-numbers/README.md
+++ b/problems/0165-compare-version-numbers/README.md
@@ -0,0 +1,85 @@
+# [165] Compare Version Numbers
+
+## 題目資訊
+- **難度**: Medium
+- **標籤**: Two Pointer, String
+- **題目連結**: https://leetcode.com/problems/compare-version-numbers/
+- **練習日期**: 2025-09-23
+- **目標複雜度**: 時間 O(n)、空間 O(1)
+
+## 題目描述
+Given two **version strings**, `version1` and `version2`, compare them. A version string consists of **revisions** separated by dots `'.'`. The **value of the revision** is its **integer conversion** ignoring leading zeros.
+
+To compare version strings, compare their revision values in **left-to-right order**. If one of the version strings has fewer revisions, treat the missing revision values as `0`.
+
+Return the following:
+
+If `version1 < version2`, return -1.
+If `version1 > version2`, return 1.
+Otherwise, return 0.
+
+## 先備條件與限制
+- 1 <= `version1.length, version2.length` <= 500
+- version1 and version2 only contain digits and '.'
+- version1 and version2 are valid version numbers.
+- All the given revisions in `version1` and `version2` can be stored in a **32-bit integer**
+
+## 解題思路
+
+### 初步分析
+- 類型：字串雙指標掃描
+- 關鍵觀察：版本號可以逐段比較，缺段視為 0，且修訂號只包含數字
+- 複雜度目標理由：只需線性掃過兩個字串一次即可完成比較
+
+### 解法比較
+1. 解法A（基準/暴力）：
+   - 名稱：`MyCompareVersion`
+   - 思路：以 `Split('.')` 將版本字串拆成陣列，逐段轉成整數後比較；若另一側段數不足以 0 補齊
+   - 正確性：LeetCode 限制每段可裝進 32-bit 整數，直接使用 `int.TryParse` 安全可靠
+   - 複雜度：時間 O(n)，空間 O(k)（k 為段數，需配置字串陣列與子字串）
+2. 解法B（優化）：
+   - 名稱：`CompareVersion`
+   - 思路：雙指標同步掃描兩個版本字串，藉由 `ReadOnlySpan<char>` 抓取下一段，去除前導 0 後用字元比較避免溢位與額外配置
+   - 正確性：段長先比較、再逐字比較，完全符合題意；缺段會回傳空 span 視為 0
+   - 複雜度：時間 O(n)，空間 O(1)
+
+## 實作細節
+
+### 常見陷阱
+- 前導 0：需在比較前移除，否則 `"01"` 與 `"1"` 會被視為不同
+- 段數不一致：右側缺少的段要視為 0
+- 空字串或末尾點：`""`、`"1."` 都可能出現，需要妥善處理
+- 非數字字元：防守性處理（當前實作視為 0），但依題意實際資料不會出現
+
+## 測試案例
+
+### 範例輸入輸出
+```
+Input: version1 = "1.2", version2 = "1.10"
+Output: -1
+Explanation:
+version1's second revision is "2" and version2's second revision is "10": 2 < 10, so version1 < version2.
+```
+
+### 邊界清單
+- [x] 空字串 / 僅有 0
+- [x] 單一段 / 全相同
+- [x] 含 0 / 大數 / 前導 0
+- [ ] 去重（與此題無關）
+- [x] 大資料壓力（長度 200 的版本字串）
+
+## 複雜度分析
+- 最壞：時間 O(n)、空間 O(1)
+- 備註：保留的 `MyCompareVersion` 雖然同為 O(n)，但空間為 O(k)
+
+## 相關題目 / Follow-up
+- 179. Largest Number：同樣涉及字串排序與比較
+- 415. Add Strings：字串逐位操作
+
+## 學習筆記
+- 今天學到：兩指標搭配 `ReadOnlySpan<char>` 可以在 C# 中避免額外配置
+- 卡住與修正：原本 console app 移除 `Main` 造成 `dotnet test` 無法編譯，後來補回精簡入口
+- 待優化：若要支援超長版本段，可考慮使用 `BigInteger` 或自訂比較邏輯（目前已以字元比較處理）
+
+---
+**總結**：核心在於逐段處理並正確處理前導 0 與缺段情況，適合練習字串雙指標與記憶體優化技巧。
--- a/problems/0165-compare-version-numbers/csharp/Program.cs
+++ b/problems/0165-compare-version-numbers/csharp/Program.cs
@@ -0,0 +1,144 @@
+// LeetCode 165: Compare Version Numbers
+// 難度: Medium
+// 日期: 2025-09-23
+
+using System;
+
+public class Solution
+{
+    // Two-pointer parser that compares segments without allocating intermediate arrays.
+    public int CompareVersion(string version1, string version2)
+    {
+        var i = 0;
+        var j = 0;
+
+        while (i < version1.Length || j < version2.Length)
+        {
+            var segment1 = NextSegment(version1, ref i);
+            var segment2 = NextSegment(version2, ref j);
+
+            var comparison = CompareSegments(segment1, segment2);
+            if (comparison != 0)
+            {
+                return comparison;
+            }
+        }
+
+        return 0;
+    }
+
+    // Reads the next numeric segment (between dots) as a span and advances the current index.
+    private static ReadOnlySpan<char> NextSegment(string version, ref int index)
+    {
+        if (index >= version.Length)
+        {
+            return ReadOnlySpan<char>.Empty;
+        }
+
+        var start = index;
+        while (index < version.Length && version[index] != '.')
+        {
+            index++;
+        }
+
+        var segment = version.AsSpan(start, index - start);
+
+        if (index < version.Length && version[index] == '.')
+        {
+            index++;
+        }
+
+        return segment;
+    }
+
+    // Compares two trimmed segments lexicographically to avoid integer overflow.
+    private static int CompareSegments(ReadOnlySpan<char> left, ReadOnlySpan<char> right)
+    {
+        left = TrimLeadingZeros(left);
+        right = TrimLeadingZeros(right);
+
+        if (left.Length > right.Length)
+        {
+            return 1;
+        }
+
+        if (left.Length < right.Length)
+        {
+            return -1;
+        }
+
+        for (var i = 0; i < left.Length; i++)
+        {
+            if (left[i] > right[i])
+            {
+                return 1;
+            }
+
+            if (left[i] < right[i])
+            {
+                return -1;
+            }
+        }
+
+        return 0;
+    }
+
+    private static ReadOnlySpan<char> TrimLeadingZeros(ReadOnlySpan<char> segment)
+    {
+        var index = 0;
+        while (index < segment.Length && segment[index] == '0')
+        {
+            index++;
+        }
+
+        return index == segment.Length ? ReadOnlySpan<char>.Empty : segment[index..];
+    }
+
+    public int MyCompareVersion(string version1, string version2)
+    {
+        var v1 = version1.Split('.');
+        var v2 = version2.Split('.');
+
+        if (v1.Length >= v2.Length)
+        {
+            return CompareString(v1, v2);
+        }
+
+        return CompareString(v2, v1) * -1;
+    }
+
+    private static int CompareString(string[] longer, string[] shorter)
+    {
+        for (var i = 0; i < longer.Length; i++)
+        {
+            _ = int.TryParse(longer[i], out var num1);
+            var num2 = i < shorter.Length && int.TryParse(shorter[i], out var parsed) ? parsed : 0;
+
+            if (num1 > num2)
+            {
+                return 1;
+            }
+
+            if (num1 < num2)
+            {
+                return -1;
+            }
+        }
+
+        return 0;
+    }
+}
+
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        // optional: keep console app functional for manual verification
+        if (args.Length == 2)
+        {
+            var solution = new Solution();
+            var result = solution.CompareVersion(args[0], args[1]);
+            Console.WriteLine(result);
+        }
+    }
+}
--- a/problems/0165-compare-version-numbers/csharp/csharp.csproj
+++ b/problems/0165-compare-version-numbers/csharp/csharp.csproj
@@ -1,10 +1,9 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
+<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
-
 </Project>
+
--- a/problems/0165-compare-version-numbers/test/SolutionTests.cs
+++ b/problems/0165-compare-version-numbers/test/SolutionTests.cs
@@ -0,0 +1,56 @@
+// LeetCode 165: Compare Version Numbers 單元測試（xUnit）
+
+using System.Linq;
+using Xunit;
+
+public class SolutionTests {
+    private readonly Solution _s = new Solution();
+
+    [Theory]
+    [InlineData("1.01", "1.001", 0)]
+    [InlineData("1.0", "1.0.0", 0)]
+    [InlineData("1.0.0.0", "1", 0)]
+    [InlineData("0.1", "1.1", -1)]
+    [InlineData("1.0.1", "1", 1)]
+    [InlineData("7.5.2.4", "7.5.3", -1)]
+    public void CompareVersion_ReturnsExpectedResult(string version1, string version2, int expected) {
+        var actual = _s.CompareVersion(version1, version2);
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Theory]
+    [InlineData("1.0.1", "1")]
+    [InlineData("3.0.0", "2.9.9.9")]
+    [InlineData("10.4", "10.3.9")]
+    public void CompareVersion_IsAntiSymmetric(string left, string right) {
+        var forward = _s.CompareVersion(left, right);
+        var backward = _s.CompareVersion(right, left);
+
+        Assert.Equal(1, forward);
+        Assert.Equal(-1, backward);
+    }
+
+    [Theory]
+    [InlineData("", "", 0)]
+    [InlineData("", "0", 0)]
+    [InlineData("0.0.0", "", 0)]
+    [InlineData("000", "0", 0)]
+    [InlineData("2147483647", "2147483646", 1)]
+    [InlineData("2147483646", "2147483647", -1)]
+    public void CompareVersion_HandlesBoundaryInputs(string version1, string version2, int expected) {
+        var actual = _s.CompareVersion(version1, version2);
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void CompareVersion_LongSequencesDifferAtEnd() {
+        var left = string.Join('.', Enumerable.Repeat("0", 199).Append("1"));
+        var right = string.Join('.', Enumerable.Repeat("0", 200));
+
+        var result = _s.CompareVersion(left, right);
+
+        Assert.Equal(1, result);
+    }
+}
--- a/problems/0165-compare-version-numbers/test/TestProject.csproj
+++ b/problems/0165-compare-version-numbers/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>
+
--- a/problems/0165-compare-version-numbers/test/edge_cases.md
+++ b/problems/0165-compare-version-numbers/test/edge_cases.md
@@ -0,0 +1,29 @@
+# 邊界情況清單（165 Compare Version Numbers）
+
+## 需要測試的邊界
+- [x] 空輸入 / 單一元素：`""`、`"0"`
+- [x] 重複元素 / 全相同：`"1.0.0"` vs `"1"`
+- [x] 極值（最小/最大）：`"2147483647"` vs `"2147483646"`
+- [x] 含負數 / 0 / 大數：題目無負數，已覆蓋多零與大修訂號
+- [x] 大資料量（接近上限）：200 段版本字串
+
+## 額外案例
+### 案例 1
+- 輸入：`version1 = "", version2 = "0"`
+- 預期：`0`
+- 說明：空字串缺少所有段，視為全 0
+
+### 案例 2
+- 輸入：`version1 = "2147483647", version2 = "2147483646"`
+- 預期：`1`
+- 說明：驗證最大 32-bit 整數段處理
+
+### 案例 3
+- 輸入：`version1 = "0.0.0", version2 = "0"`
+- 預期：`0`
+- 說明：多段全 0 與單段 0 視為相同
+
+### 案例 4
+- 輸入：`version1 = string.Join(".", Enumerable.Repeat("0", 199)) + ".1"`, `version2 = string.Join(".", Enumerable.Repeat("0", 200))`
+- 預期：`1`
+- 說明：長度 200 的版本字串，在最後一段差異才分勝負
--- a/problems/0166-fraction-to-recurring-decimal/0166-fraction-to-recurring-decimal.sln
+++ b/problems/0166-fraction-to-recurring-decimal/0166-fraction-to-recurring-decimal.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 = {C5790EDA-C36F-4FC3-877D-C7E20837E160}
+	EndGlobalSection
+EndGlobal
--- a/problems/0166-fraction-to-recurring-decimal/README.md
+++ b/problems/0166-fraction-to-recurring-decimal/README.md
@@ -0,0 +1,80 @@
+# [166] Fraction To Recurring Decimal
+
+## 題目資訊
+- **難度**: Medium
+- **標籤**: Hash Table, Math, Simulation
+- **題目連結**: https://leetcode.com/problems/fraction-to-recurring-decimal/
+- **練習日期**: 2025-09-24
+- **目標複雜度**: 時間 O(L)、空間 O(L)（L 為輸出字串長度，最多 10^4）
+
+## 題目描述
+Given two integers representing the `numerator` and `denominator` of a fraction, return *the fraction* in string format.
+
+If the fractional part is repeating, enclose the repeating part in parentheses.
+
+If multiple answers are possible, return **any of them**.
+
+It is **guaranteed** that the length of the answer string is less than `10^4` for all the given inputs.
+
+## 先備條件與限制
+- 輸入限制：`-2^31 <= numerator, denominator <= 2^31 - 1`，且 denominator ≠ 0
+- 回傳/輸出格式：回傳十進位字串；有限小數直接輸出，小數有循環時用括號標記循環段
+- 其他：允許使用 64-bit 以避免在取絕對值時溢位
+
+## 解題思路
+
+### 初步分析
+- 類型：數學 / 模擬 / 哈希
+- 關鍵觀察：整數除法僅靠餘數決定下一個小數位；相同餘數必定導致循環，位置可透過哈希表還原
+- 複雜度目標理由：每個餘數最多處理一次，因此時間與空間成正比於輸出長度 L
+
+### 解法比較
+1. 解法A：餘數位置哈希
+   - 思路：先處理正負號並計算整數部分；對小數部分反覆以 10 乘上餘數取商，並在 map 中紀錄餘數首次出現的索引，一旦重複即可插入括號
+   - 正確性：每個可能的餘數介於 0 與 |denominator|-1，重複時即代表循環節開始，未重複則最後餘數為 0（有限小數）
+   - 複雜度：時間 O(L) / 空間 O(L)
+
+## 實作細節
+- 先處理 `numerator == 0` 直接回傳 "0"
+- 判斷結果正負號，使用 `long`/`long long` 取絕對值避免 `INT_MIN` 無法轉正的問題
+- `integer_part = abs_num / abs_den` 直接加入結果，小數部分以餘數 `remainder = abs_num % abs_den` 開始
+- 使用字典 `remainder -> index` 紀錄餘數在結果字串中的位置；迴圈內：餘數乘 10，取下一位商並更新餘數
+- 若餘數為 0，表示小數結束，不需括號；若餘數再度出現，在對應索引插入 `(`，在結尾加 `)`
+
+## 常見陷阱
+- 處理負數：符號只出現一次，判斷後用 64-bit 絕對值繼續運算避免 `--6...` 之類錯誤
+- `INT_MIN / -1` 可能溢位：需先轉成 64-bit 再做除法與取餘數
+- 餘數 map 要記錄的是「餘數出現時的輸出索引」，找到重複時要在該位置插入 `(`
+- 每回合先檢查餘數是否重複再乘 10，避免多插一位或落掉循環起點
+- `numerator` 為 0 時無小數部分，直接回傳 "0"
+
+## 測試案例
+
+### 範例輸入輸出
+```
+Input: numerator = 4, denominator = 333
+Output: "0.(012)"
+```
+
+### 邊界清單
+- `numerator = 1, denominator = 2` → `"0.5"`（有限小數）
+- `numerator = 1, denominator = 6` → `"0.1(6)"`（循環節不從第一位開始）
+- `numerator = -50, denominator = 8` → `"-6.25"`（負數與有限小數）
+- `numerator = 0, denominator = 5` → `"0"`（整數結果）
+- `numerator = 1, denominator = 7` → `"0.(142857)"`（較長的循環節）
+
+## 複雜度分析
+- 最壞：時間 O(L)、空間 O(L)
+- L 為輸出字串長度，等同於需要處理的餘數數量上限（題目保證 < 10^4）
+
+## 相關題目 / Follow-up
+- 與任一進位制的循環小數檢測（如 base conversion）類似，可類比餘數循環檢測技巧
+
+## 學習筆記
+- 今天學到：餘數 → 索引的哈希表能精準標記循環段，搭配 `StringBuilder.Insert` 可快速加括號
+- 卡住與修正：`int.MinValue` 轉正時會拋例外，改用 `long` 做完整流程（含乘 10 與取餘）就穩定
+- 另外注意：符號在輸出開頭先處理，整數和小數部分都用正數運算可避免重複符號
+- 待優化：可以先行預估非循環長度以減少插入成本，但對此題影響不大
+
+---
+**總結**：這題的核心在於以餘數哈希判斷循環節，適合練習小數表示與溢位處理。
--- a/problems/0166-fraction-to-recurring-decimal/csharp/Program.cs
+++ b/problems/0166-fraction-to-recurring-decimal/csharp/Program.cs
@@ -0,0 +1,68 @@
+// LeetCode 166: Fraction To Recurring Decimal
+// 難度: Medium
+// 日期: 2025-09-24
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+public class Solution
+{
+    public string FractionToDecimal(int numerator, int denominator)
+    {
+        if (numerator == 0) return "0";
+
+        long num = numerator;
+        long den = denominator;
+
+        StringBuilder result = new StringBuilder();
+        bool isNegative = (num < 0) ^ (den < 0);
+        if (isNegative) result.Append('-');
+
+        num = Math.Abs(num);
+        den = Math.Abs(den);
+
+        long integerPart = num / den;
+        result.Append(integerPart);
+
+        long remainder = num % den;
+        if (remainder == 0) return result.ToString();
+
+        result.Append('.');
+        result.Append(CalculateDecimalPart(remainder, den));
+
+        return result.ToString();
+    }
+
+    private string CalculateDecimalPart(long remainder, long denominator)
+    {
+        StringBuilder decimalBuilder = new StringBuilder();
+        Dictionary<long, int> remainderMap = new Dictionary<long, int>();
+
+        while (remainder != 0)
+        {
+            if (remainderMap.TryGetValue(remainder, out int repeatIndex))
+            {
+                decimalBuilder.Insert(repeatIndex, '(');
+                decimalBuilder.Append(')');
+                break;
+            }
+
+            remainderMap[remainder] = decimalBuilder.Length;
+            remainder *= 10;
+            long digit = remainder / denominator;
+            decimalBuilder.Append(digit);
+            remainder %= denominator;
+        }
+
+        return decimalBuilder.ToString();
+    }
+}
+
+public class Program {
+    public static void Main() {
+        var s = new Solution();
+        
+    }
+}
--- a/problems/0166-fraction-to-recurring-decimal/csharp/csharp.csproj
+++ b/problems/0166-fraction-to-recurring-decimal/csharp/csharp.csproj
@@ -1,10 +1,9 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
+<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
-
 </Project>
+
--- a/problems/0166-fraction-to-recurring-decimal/go/go.mod
+++ b/problems/0166-fraction-to-recurring-decimal/go/go.mod
@@ -0,0 +1,3 @@
+module leetcode-166
+
+go 1.18
--- a/problems/0166-fraction-to-recurring-decimal/go/main.go
+++ b/problems/0166-fraction-to-recurring-decimal/go/main.go
@@ -0,0 +1,18 @@
+// LeetCode 166: Fraction To Recurring Decimal
+// 難度: Medium
+// 日期: 2025-09-24
+
+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 166!\n")
+    // TODO: 可加入簡單測試
+}
+
--- a/problems/0166-fraction-to-recurring-decimal/test/SolutionTests.cs
+++ b/problems/0166-fraction-to-recurring-decimal/test/SolutionTests.cs
@@ -0,0 +1,27 @@
+// LeetCode 166 單元測試（xUnit）
+
+using Xunit;
+
+public class SolutionTests {
+    private readonly Solution _s = new Solution();
+
+    [Theory]
+    [InlineData(4, 333, "0.(012)")]
+    [InlineData(1, 2, "0.5")]
+    [InlineData(1, 6, "0.1(6)")]
+    [InlineData(-50, 8, "-6.25")]
+    [InlineData(0, 5, "0")]
+    [InlineData(1, 7, "0.(142857)")]
+    public void FractionToDecimal_BasicAndRepeatingScenarios(int numerator, int denominator, string expected) {
+        var actual = _s.FractionToDecimal(numerator, denominator);
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void FractionToDecimal_DenominatorOne_ReturnsIntegerString() {
+        var actual = _s.FractionToDecimal(2, 1);
+
+        Assert.Equal("2", actual);
+    }
+}
--- a/problems/0166-fraction-to-recurring-decimal/test/TestProject.csproj
+++ b/problems/0166-fraction-to-recurring-decimal/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>
+
--- a/problems/0166-fraction-to-recurring-decimal/test/edge_cases.md
+++ b/problems/0166-fraction-to-recurring-decimal/test/edge_cases.md
@@ -0,0 +1,20 @@
+# 邊界情況清單（166 Fraction To Recurring Decimal）
+
+## 需要測試的邊界
+- [ ] 空輸入 / 單一元素
+- [ ] 重複元素 / 全相同
+- [ ] 極值（最小/最大）
+- [ ] 含負數 / 0 / 大數
+- [ ] 大資料量（接近上限）
+
+## 額外案例
+### 案例 1
+- 輸入：
+- 預期：
+- 說明：
+
+### 案例 2
+- 輸入：
+- 預期：
+- 說明：
+
--- a/problems/0166-fraction-to-recurring-decimal/test/main_test.go
+++ b/problems/0166-fraction-to-recurring-decimal/test/main_test.go
@@ -0,0 +1,12 @@
+// LeetCode 166 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) }
+}
+
--- a/problems/3005-count_elements_with_maximum_frequency/3005-count_elements_with_maximum_frequency.sln
+++ b/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
--- a/problems/3005-count_elements_with_maximum_frequency/README.md
+++ b/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 ______。
+
--- a/problems/3005-count_elements_with_maximum_frequency/csharp/Program.cs
+++ b/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!");
+    }
+}
+
--- a/problems/3005-count_elements_with_maximum_frequency/csharp/csharp.csproj
+++ b/problems/3005-count_elements_with_maximum_frequency/csharp/csharp.csproj
@@ -1,10 +1,9 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
+<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
-
 </Project>
+
--- a/problems/3005-count_elements_with_maximum_frequency/go/main.go
+++ b/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
+}
+
--- a/problems/3005-count_elements_with_maximum_frequency/test/SolutionTests.cs
+++ b/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);
+    }
+}
+
--- a/problems/3005-count_elements_with_maximum_frequency/test/TestProject.csproj
+++ b/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>
+
--- a/problems/3005-count_elements_with_maximum_frequency/test/main_test.go
+++ b/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) }
+}
+
--- a/problems/3227-vowels-game-in-a-string/README.md
+++ b/problems/3227-vowels-game-in-a-string/README.md
@@ -21,56 +21,56 @@ Return `true` if Alice wins the game, and `false` otherwise.
 The English vowels are: `a`, `e`, `i`, `o`, and `u`.

 ## 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
+- 輸入限制：n ∈ [1, 10^5]、字符為小寫英文字母
+- 回傳/輸出格式：boolean 值，true 表示 Alice 獲勝

 ## 解題思路

 ### 初步分析
- 類型：雙指針 / 滑動視窗 / 排序 / DP / 貪心 / 圖論 ...
+- 類型：博弈論 / 數學 / 腦筋急轉彎
 - 關鍵觀察：
- 複雜度目標理由：
+   - Alice 先手，需移除含奇數個母音的子字串
+   - Bob 後手，需移除含偶數個母音的子字串
+- 複雜度目標理由：只需檢查是否存在母音

 ### 解法比較
 1. 解法A（基準/暴力）：
   - 思路：
+      發現 Alice 獲勝條件極其簡單
   - 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：...
+      只需檢查是否存在母音
+   - 複雜度：O(n) / O(1) 

 ### 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
+- 邊界：空字串（題目保證 n≥1）、全母音、無母音
+- 過度複雜化：誤以為需要複雜的博弈分析
+- 計數錯誤：誤以為需要精確計算母音數量
+- 大小寫：題目保證小寫字母

 ## 測試案例

 ### 範例輸入輸出
 ```
-Input: ...
-Output: ...
-Explanation: ...
+Input: s = "leetcode"
+Output: true
+Explanation: Alice 可以移除 "leetcod"（含3個母音），剩下 "e"，Bob 無法移除含偶數母音的子字串
 ```

 ### 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
+- 全母音字串：Alice 立即移除整個字串獲勝
+- 無母音字串：Alice 無法行動敗北
+- 單一字符（母音/子音）
+- 混合字串（含有母音和子音）
+- 長字串壓力測試

 ## 複雜度分析
- 最壞：時間 O(?)、空間 O(?)
+- 最壞：時間 O(n)、空間 O(1)
+- 最佳：時間 O(1)（首字符即為母音）、空間 O(1)

 ## 相關題目 / Follow-up
- 
+- LeetCode 345: Reverse Vowels of a String
+- LeetCode 1456: Maximum Number of Vowels in a Substring of Given Length
+- LeetCode 2062: Count Vowel Substrings of a String

 ## 學習筆記
 - 今天學到：
Author	SHA1	Message	Date
MH Hung	8146e2176d	[#0166 ] feat(leetcode): add README, unit test and C# solution	2025-09-24 11:18:08 +08:00
MH Hung	5189c524ef	[#0166 ] feat(leetcode): init project	2025-09-24 09:35:00 +08:00
MH Hung	959f8a6861	remove: legacy solutions	2025-09-24 09:34:13 +08:00
MH Hung	5f8bf18795	docs(monthly): update monthly report	2025-09-23 11:02:46 +08:00
MH Hung	72aa011de9	[#0165 ]feat(leetcode): Init project, add C# solution, unit test and README	2025-09-23 10:59:18 +08:00
MH Hung	c4e23d5be3	docs(monthly): update monthly report	2025-09-22 13:51:44 +08:00
MH Hung	c7453b45e6	[#3005 ] feat(leetcode): init project, add C# solution	2025-09-22 13:48:38 +08:00
MH Hung	7c86a4a99a	feat(makefile): makefile for automatic setup	2025-09-22 09:58:24 +08:00
MH Hung	c396a84294	docs(logs): update monthly log	2025-09-12 13:37:31 +08:00
MH Hung	2d6209a043	[#3227 ] docs(leetcode): update README	2025-09-12 13:34:05 +08:00