feat(env): String Synthesis Curriculum (#308)

* string synthesis curriculum

* difficulty metadata

reasoning_gym/algorithmic/string_synthesis.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 = """There are nine different blocks [A] [B] [C] {{A}} {{B}} {{C}} (A) (B) (C)
@@ -24,6 +25,7 @@ The output should be the count of each block type after the rules have been appl
 For example 1 0 3 0 2 0 0 0 1 means that you have 1 [A] 0 [B] 3 [C] 0 {{A}} 2 {{B}} 0 {{C}} 0 (A) 0 (B) 1 (C).
 
 Now, you have {A_square} [A], {B_square} [B], and {C_square} [C] blocks. Provide the count of each block type after applying the above rules.
+Note: Apply the rules at most {max_iterations} times. If the rules cannot be applied anymore, or if you have reached the maximum number of iterations, stop and provide the current counts.
 """
 
 
@@ -120,10 +122,40 @@ class StringSynthesisDataset(ProceduralDataset):
         answer_str = " ".join(str(x) for x in answer)
 
         return {
-            "question": QUESTION_TEMPLATE.format(A_square=A_square, B_square=B_square, C_square=C_square),
+            "question": QUESTION_TEMPLATE.format(
+                A_square=A_square,
+                B_square=B_square,
+                C_square=C_square,
+                max_iterations=self.config.max_iterations,
+            ),
             "answer": answer_str,
-            "metadata": {"states": states, "solution": answer},
+            "metadata": {
+                "states": states,
+                "solution": answer,
+                "difficulty": {
+                    "initial_blocks": (A_square, B_square, C_square),
+                },
+            },
         }
 
 
-register_dataset("string_synthesis", StringSynthesisDataset, StringSynthesisConfig)
+class StringSynthesisCurriculum(BaseCurriculum):
+    def __init__(self):
+        super().__init__(StringSynthesisCurriculum.__name__, StringSynthesisConfig)
+
+        # Define attributes
+        self._define_attributes(
+            RangeAttributeDefinition(
+                name="initial_blocks",
+                levels=[10, 50, 100, 500],
+                default_level=1,
+                description="Number of initial blocks",
+                attr_type=AttributeType.APPEND,
+                min_value=0,
+                lower_field_name="min_initial_blocks",
+                upper_field_name="max_initial_blocks",
+            )
+        )
+
+
+register_dataset("string_synthesis", StringSynthesisDataset, StringSynthesisConfig, StringSynthesisCurriculum)