Create solver_remainder.py

solver_remainder.py

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+from __future__ import annotations
+
+import re
+from typing import Optional
+
+from models import SolverResult
+
+
+def solve_remainder(text: str) -> Optional[SolverResult]:
+    lower = (text or "").lower()
+
+    if "remainder" not in lower and "mod" not in lower:
+        return None
+
+    # "remainder when 17 is divided by 5"
+    m = re.search(
+        r"remainder.*?when\s+(-?\d+)\s+(?:is\s+)?divided\s+by\s+(-?\d+)",
+        lower,
+    )
+    if not m:
+        m = re.search(
+            r"(-?\d+)\s*(?:mod|%)\s*(-?\d+)",
+            lower,
+        )
+
+    if m:
+        a = int(m.group(1))
+        b = int(m.group(2))
+        if b == 0:
+            return None
+        result = a % b
+        return SolverResult(
+            domain="quant",
+            solved=True,
+            topic="remainder",
+            answer_value=str(result),
+            internal_answer=str(result),
+            steps=[
+                "Use the division algorithm.",
+                "The remainder is what is left after dividing by the divisor.",
+            ],
+        )
+
+    # "When n is divided by 5 the remainder is 2. What is remainder when 3n is divided by 5?"
+    m = re.search(
+        r"remainder\s+is\s+(\d+).*?what\s+is\s+the\s+remainder\s+when\s+(\d+)n\s+is\s+divided\s+by\s+(\d+)",
+        lower,
+    )
+    if m:
+        r = int(m.group(1))
+        mult = int(m.group(2))
+        mod = int(m.group(3))
+        result = (mult * r) % mod
+        return SolverResult(
+            domain="quant",
+            solved=True,
+            topic="remainder",
+            answer_value=str(result),
+            internal_answer=str(result),
+            steps=[
+                "Replace n by its remainder class modulo the divisor.",
+                "Multiply the remainder and reduce again modulo the divisor.",
+            ],
+        )
+
+    return None