diff --git a/problems/3027-find-the-number-of-ways-to-place-people-ii/csharp/Program.cs b/problems/3027-find-the-number-of-ways-to-place-people-ii/csharp/Program.cs
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+// LeetCode 3027: Find The Number Of Ways To Place People Ii
+// 難度: Hard
+// 日期: 2025-09-03
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public class Solution {
+    public int NumberOfPairs(int[][] points)
+    {
+        int n = points.Length;
+        int result = 0;
+
+        for (var i = 0; i < n; i++)
+        {
+            for (var j = 0; j < n; j++)
+            {
+                if (i == j) continue;
+
+                // 判斷 Alice points[i] 是否在 Bob points[j] 左上角
+                var Alice = points[i];
+                var Bob = points[j];
+                if (Alice[0] <= Bob[0] && Alice[1] >= Bob[1])
+                {
+                    // get border
+                    int minX = Alice[0];
+                    int maxX = Bob[0];
+                    int minY = Bob[1];
+                    int maxY = Alice[1];
+                    bool isAnyPerson = false;
+
+                    for (var k = 0; k < n; k++)
+                    {
+                        if (i == k || j == k) continue;
+
+                        var person = points[k];
+                        if (minX <= person[0] && person[0] <= maxX && minY <= person[1] && person[1] <= maxY)
+                        {
+                            isAnyPerson = true;
+                            break;
+                        }
+                    }
+
+                    if (!isAnyPerson) result++;
+                }
+            }
+        }
+        return result;
+    }
+}
+
+public class Program {
+    public static void Main() {
+        Solution solution = new Solution();
+
+        // 測試案例
+        TestCase(solution);
+    }
+    
+    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($"Test Case: [[6,2],[4,4],[2,6]]");
+        Console.WriteLine($"Expected: 2");
+
+        // Actual: 
+        int result1 = solution.NumberOfPairs(points);
+        Console.WriteLine($"Result: {result1}");
+    }
+}
diff --git a/problems/3027-find-the-number-of-ways-to-place-people-ii/csharp/csharp.csproj b/problems/3027-find-the-number-of-ways-to-place-people-ii/csharp/csharp.csproj
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--- /dev/null
+++ b/problems/3027-find-the-number-of-ways-to-place-people-ii/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>