feat(env): Binary Alternation Curriculum (#278)

* binary alternation

---------

Co-authored-by: Andreas Koepf <andreas.koepf@provisio.com>

reasoning_gym/algorithmic/binary_alternation.py

@@ -7,6 +7,7 @@ from dataclasses import dataclass
 from random import Random
 from typing import Optional
 
+from ..coaching import AttributeType, BaseCurriculum, RangeAttributeDefinition
 from ..factory import ProceduralDataset, register_dataset
 
 QUESTION_TEMPLATE = """Given a binary string, return the minimum number of character swaps to make it alternating, or -1 if it is impossible.
@@ -43,8 +44,7 @@ class BinaryAlternationDataset(ProceduralDataset):
     def __init__(self, config: BinaryAlternationConfig):
         super().__init__(config=config, seed=config.seed, size=config.size)
 
-    def _get_binary_string(self, rng: Random, solvable: bool) -> str:
-        n = rng.randint(self.config.min_n, self.config.max_n)
+    def _get_binary_string(self, rng: Random, n: int, solvable: bool) -> str:
         ones, zeros = n // 2, n // 2
 
         # Check if we need to add an extra bit
@@ -96,15 +96,40 @@ class BinaryAlternationDataset(ProceduralDataset):
         """Generate a single Count Bits question"""
         rng = Random(self.seed + idx)
 
+        n = rng.randint(self.config.min_n, self.config.max_n)
         solvable = rng.random() < self.config.p_solvable
-        string = self._get_binary_string(rng, solvable)
+        string = self._get_binary_string(rng, n, solvable)
         answer = self._get_answer(string)
 
         return {
             "question": QUESTION_TEMPLATE.format(string=string),
             "answer": str(answer),
-            "metadata": {"string": string, "solution": answer, "solvable": solvable},
+            "metadata": {
+                "string": string,
+                "solution": answer,
+                "solvable": solvable,
+                "difficulty": {"n": n},
+            },
         }
 
 
-register_dataset("binary_alternation", BinaryAlternationDataset, BinaryAlternationConfig)
+class BinaryAlternationCurriculum(BaseCurriculum):
+    def __init__(self):
+        super().__init__(BinaryAlternationCurriculum.__name__, BinaryAlternationConfig)
+
+        # Define attributes
+        self._define_attributes(
+            RangeAttributeDefinition(
+                name="n",
+                levels=[10, 50, 500, 1000],
+                default_level=0,
+                description="Number of bits in the binary string",
+                attr_type=AttributeType.APPEND,
+                min_value=1,
+                lower_field_name="min_n",
+                upper_field_name="max_n",
+            )
+        )
+
+
+register_dataset("binary_alternation", BinaryAlternationDataset, BinaryAlternationConfig, BinaryAlternationCurriculum)