[#3025] note(numberOfPairs): add Description and init C# project

problems/3025-find-the-number-of-ways-to-place-people-i/README.md

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+# [3025] Find The Number Of Ways To Place People I
+
+## 題目資訊
+- **難度**: Medium
+- **標籤**: Array, Math, Geometry, Sorting, Enumeration
+- **題目連結**: [LeetCode](https://leetcode.com/problems/find-the-number-of-ways-to-place-people-i/)
+- **練習日期**: 2025-09-02
+
+## 題目描述
+You are given a 2D array `points` of size `n x 2` representing integer coordinates of some points on a 2D plane, where `points[i] = [xi, yi]`.
+
+Count the number of pairs of points `(A, B)`, where
+ - `A` is on **the upper** left side of `B`, and
+ - there are no other points in the rectangle (or line) they make (**including the border**).
+
+Return the count.
+
+## 解題思路
+
+### 初步分析
+- 這題主要考察什麼概念？
+- 有什麼關鍵限制條件？
+- 預期時間/空間複雜度？
+
+### 解法概述
+1. **暴力解法**: 
+   - 思路：
+   - 時間複雜度：O(?)
+   - 空間複雜度：O(?)
+   
+2. **優化解法**: 
+   - 思路：
+   - 時間複雜度：O(?)
+   - 空間複雜度：O(?)
+
+## 測試案例
+
+### 範例輸入輸出
+```
+Input: points = [[6,2],[4,4],[2,6]]
+Output: 2
+Explanation:
+ - The left one is the pair (points[1], points[0]), where points[1] is on the upper left side of points[0] and the rectangle is empty.
+ - The left one is the pair (points[1], points[0]), where points[1] is on the upper left side of points[0] and the rectangle is empty.
+ - The right one is the pair (points[2], points[0]), where points[2] is on the upper left side of points[0], but points[1] is inside the rectangle so it's not a valid pair.
+```
+
+### 邊界情況
+- `2 <= n <= 50`
+- `points[i].length == 2`
+- `0 <= points[i][0], points[i][1] <= 50`
+- All `points[i]` are distinct.
+
+## 學習筆記
+
+### 今天學到什麼？
+- 
+
+### 遇到的困難
+- 
+
+### 改善方向
+- 
+
+### 相關題目
+- [題目編號] 題目名稱 - 相似概念
+- [題目編號] 題目名稱 - 進階版本
+
+---
+**總結**: 這題的核心概念是...，適合練習...技巧。

problems/3025-find-the-number-of-ways-to-place-people-i/csharp/Program.cs

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+// LeetCode 3025: Find The Number Of Ways To Place People I
+// 難度: Medium
+// 日期: 2025-09-02
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public class Solution {
+    public void Solve() {
+        // TODO: 實作解法
+        Console.WriteLine("Hello LeetCode 3025!");
+    }
+}
+
+// 測試程式
+public class Program {
+    public static void Main() {
+        Solution sol = new Solution();
+        sol.Solve();
+        
+        // TODO: 加入測試案例
+        // TestCase1();
+        // TestCase2();
+    }
+    
+    // 測試案例模板
+    /*
+    static void TestCase1() {
+        // Input: 
+        // Expected: 
+        // Actual: 
+        Console.WriteLine("Test 1: ");
+    }
+    */
+}

problems/3025-find-the-number-of-ways-to-place-people-i/csharp/csharp.csproj

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

problems/3025-find-the-number-of-ways-to-place-people-i/test/SolutionTests.cs

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+// LeetCode 3025 單元測試
+// 使用 xUnit 框架
+
+using Xunit;
+using System;
+using System.Collections.Generic;
+
+public class SolutionTests {
+    private readonly Solution _solution;
+    
+    public SolutionTests() {
+        _solution = new Solution();
+    }
+    
+    [Fact]
+    public void TestCase1() {
+        // Arrange
+        // TODO: 設定輸入資料
+        // var input = ;
+        // var expected = ;
+        
+        // Act
+        // var result = _solution.YourMethod(input);
+        
+        // Assert
+        // Assert.Equal(expected, result);
+        
+        Assert.True(true); // 暫時通過，等待實作
+    }
+    
+    [Fact]
+    public void TestCase2() {
+        // TODO: 第二個測試案例
+        Assert.True(true);
+    }
+    
+    [Fact]
+    public void TestEdgeCases() {
+        // TODO: 邊界情況測試
+        // 空陣列、單一元素、最大值、最小值等
+        Assert.True(true);
+    }
+}

problems/3025-find-the-number-of-ways-to-place-people-i/test/TestProject.csproj

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+<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/3025-find-the-number-of-ways-to-place-people-i/test/edge_cases.md

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+# 邊界情況清單
+
+## 需要測試的邊界情況
+- [ ] 空輸入 (空陣列、空字串等)
+- [ ] 單一元素
+- [ ] 重複元素  
+- [ ] 最大值/最小值
+- [ ] 負數情況
+- [ ] 超大資料量
+- [ ] 特殊字符 (如果是字串題目)
+
+## 額外測試案例
+### 案例 1:
+**輸入**: 
+**輸出**: 
+**說明**: 
+
+### 案例 2:
+**輸入**: 
+**輸出**: 
+**說明**: