diff --git a/problems/3025-find-the-number-of-ways-to-place-people-i/README.md b/problems/3025-find-the-number-of-ways-to-place-people-i/README.md
index 053c910..aee914d 100644
--- a/problems/3025-find-the-number-of-ways-to-place-people-i/README.md
+++ b/problems/3025-find-the-number-of-ways-to-place-people-i/README.md
@@ -18,14 +18,19 @@ 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？
+- 核心概念
+   幾何關係判斷 + 區域內點的檢測
+- 關鍵限制條件
+   1. A必須在B的左上方, A.x <= B.x, A.y >= B.y
+   2. 矩形區域內（包含邊界）不能有其他點
 - 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(?)
+      - 遍歷所有點對 (A, B)
+      - 檢查每個pair形成的矩形, 裡面跟邊界會不會包含其他點
+   - 時間複雜度：O(N^3)
    - 空間複雜度：O(?)
    
 2. **優化解法**: 
@@ -54,17 +59,16 @@ Explanation:
 ## 學習筆記
 
 ### 今天學到什麼？
-- 
+- 二維空間判斷點大小
 
 ### 遇到的困難
-- 
+- 無
 
 ### 改善方向
-- 
+- 無
 
 ### 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
+- [#223](https://leetcode.com/problems/rectangle-area/) Rectangle Area
 
 ---
 **總結**: 這題的核心概念是...，適合練習...技巧。
diff --git a/problems/3025-find-the-number-of-ways-to-place-people-i/csharp/Program.cs b/problems/3025-find-the-number-of-ways-to-place-people-i/csharp/Program.cs
index 62d8ffc..8b43681 100644
--- a/problems/3025-find-the-number-of-ways-to-place-people-i/csharp/Program.cs
+++ b/problems/3025-find-the-number-of-ways-to-place-people-i/csharp/Program.cs
@@ -4,33 +4,83 @@
 
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 using System.Linq;
 
-public class Solution {
-    public void Solve() {
-        // TODO: 實作解法
-        Console.WriteLine("Hello LeetCode 3025!");
+public class Solution
+{
+    public int NumberOfPairsWithBruteForce(int[][] points)
+    {
+        // 遍歷所有點對 (A, B)
+        // 檢查每個pair形成的矩形, 裡面跟邊界會不會包含其他點
+
+        // points[0].Length == 2
+        int n = points.Length;
+        int count = 0;
+
+        for (var i = 0; i < n; i++)
+        {
+            for (var j = 0; j < n; j++)
+            {
+                if (i == j) continue;
+
+                int[] pointA = points[i];
+                int[] pointB = points[j];
+
+                // check if A.x <= B.x && A.y >= B.y
+                // if yes, check if any points in rectangle
+                if (pointA[0] <= pointB[0] && pointA[1] >= pointB[1])
+                {
+                    // difinition of border
+                    bool hasOtherPoint = false;
+                    int minX = pointA[0];
+                    int maxX = pointB[0];
+                    int minY = pointB[1];
+                    int maxY = pointA[1];
+
+                    // check other point if its in border
+                    for (var k = 0; k < n; k++)
+                    {
+                        if (k == i || k == j) continue;
+
+                        var pointC = points[k];
+                        if (minX <= pointC[0] && pointC[0] <= maxX
+                            && minY <= pointC[1] && pointC[1] <= maxY)
+                        {
+                            hasOtherPoint = true;
+                            break;
+                        }
+                    }
+
+                    if (!hasOtherPoint) count++;
+                }
+            }
+        }
+        return count;
     }
 }
 
-// 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();
+        Solution solution = new Solution();
+
+        // 測試案例
+        TestCase(solution);
     }
     
-    // 測試案例模板
-    /*
-    static void TestCase1() {
+    static void TestCase(Solution solution) {
         // Input: 
+        int[][] points = new int[][] {
+            new int[] {6, 2},
+            new int[] {4, 4},
+            new int[] {2, 6}
+        };
         // Expected: 
+        Console.WriteLine($"測試案例 1: [[6,2],[4,4],[2,6]]");
+        Console.WriteLine($"預期: 2");
+
         // Actual: 
-        Console.WriteLine("Test 1: ");
+        int result1 = solution.NumberOfPairsWithBruteForce(points);
+        Console.WriteLine($"Brute Force: {result1}");
     }
-    */
 }