Added first code.

Signed-off-by: Naoriel Sa' Rocí <naoriel@sa-roci.de>

Services/QuestionGenerator.cs

@@ -0,0 +1,33 @@
+using EinmaleinsTrainer.Models;
+using System;
+using System.Linq;
+using System.Collections.Generic;
+
+namespace EinmaleinsTrainer.Services;
+
+public class QuestionGenerator
+{
+    private readonly Random _random = new();
+
+    public List<Question> Generate(List<int> rows, bool includeSquares)
+    {
+        var pool = new List<Question>();
+
+        foreach (var r in rows)
+        {
+            for (int i = 1; i <= 10; i++)
+                pool.Add(new Question { A = r, B = i });
+        }
+
+        if (includeSquares)
+        {
+            for (int i = 1; i <= 10; i++)
+                pool.Add(new Question { A = i, B = i });
+        }
+
+        return pool.OrderBy(_ => _random.Next())
+                   .Take(10)
+                   .ToList();
+    }
+}
+