feat: Enhance GCD dataset to retry generating numbers with GCD > 1

reasoning_gym/arithmetic/gcd.py

@@ -46,23 +46,29 @@ class GCDDataset:
         self._current_idx += 1
         return item
 
-    def _generate_numbers(self, rng: Random) -> List[int]:
-        """Generate a list of random positive integers"""
+    def _generate_numbers(self, rng: Random) -> Tuple[List[int], int]:
+        """Generate a list of random positive integers and their GCD.
+        Will try up to 3 times to find numbers with GCD > 1."""
+        for _ in range(3):  # Try up to 3 times to get GCD > 1
+            num_count = rng.randint(self.config.min_numbers, self.config.max_numbers)
+            numbers = [rng.randint(self.config.min_value, self.config.max_value) 
+                      for _ in range(num_count)]
+            result = reduce(gcd, numbers)
+            if result > 1:
+                return numbers, result
+        
+        # If we failed to find GCD > 1 after 3 tries, generate one final set
         num_count = rng.randint(self.config.min_numbers, self.config.max_numbers)
-        return [rng.randint(self.config.min_value, self.config.max_value) 
-                for _ in range(num_count)]
-
-    def _calculate_gcd(self, numbers: List[int]) -> int:
-        """Calculate the GCD of a list of numbers"""
-        return reduce(gcd, numbers)
+        numbers = [rng.randint(self.config.min_value, self.config.max_value) 
+                  for _ in range(num_count)]
+        result = reduce(gcd, numbers)
+        return numbers, result
 
     def __getitem__(self, idx: int) -> dict:
         """Generate a single GCD task"""
         rng = Random(self.seed + idx)
         
-        numbers = self._generate_numbers(rng)
-        result = self._calculate_gcd(numbers)
-        
+        numbers, result = self._generate_numbers(rng)
         numbers_str = ", ".join(str(n) for n in numbers)
         
         return {