Merge pull request steam-bell-92#797 from dhruvpatel16120/fix-recognizer-agp

fix: resolve degenerate AGP recognition for zero-ratio sequences (steam-bell-92#637)

Author: steam-bell-92

math/AP-GP-AGP-HP-Recognizer/AP-GP-AGP-HP-Recognizer.py

@@ -95,9 +95,17 @@ def agp_candidates(sequence):
 
 def check_agp(sequence):
     for ratio in agp_candidates(sequence):
+        a = sequence[0]
+        if is_close(ratio, 0.0):
+            # If common ratio r = 0, all terms from index 1 onwards must be 0
+            if all(is_close(x, 0.0) for x in sequence[1:]):
+                return True, ratio
+            continue
+
+        d = (sequence[1] / ratio) - a
         valid = True
-        for i in range(2, len(sequence)):
-            expected = 2 * ratio * sequence[i - 1] - (ratio * ratio) * sequence[i - 2]
+        for i in range(len(sequence)):
+            expected = (a + i * d) * (ratio ** i)
             if not is_close(sequence[i], expected, eps=1e-7):
                 valid = False
                 break

tests/test_progression_recognizer.py

@@ -0,0 +1,56 @@
+import unittest
+import subprocess
+import os
+import sys
+
+class TestProgressionRecognizer(unittest.TestCase):
+    def setUp(self):
+        self.script_path = os.path.join("math", "AP-GP-AGP-HP-Recognizer", "AP-GP-AGP-HP-Recognizer.py")
+
+    def run_script_with_input(self, user_input):
+        process = subprocess.Popen(
+            [sys.executable, self.script_path],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            text=True
+        )
+        stdout, stderr = process.communicate(input=user_input)
+        return stdout, stderr
+
+    def test_ap_sequence(self):
+        # Choice 1 for Recognize sequence type, then the AP sequence, then 2 to exit
+        user_input = "1\n2, 4, 6, 8\n2\n"
+        stdout, _ = self.run_script_with_input(user_input)
+        self.assertIn("AP (common difference d = 2)", stdout)
+
+    def test_gp_sequence(self):
+        user_input = "1\n3, 6, 12, 24\n2\n"
+        stdout, _ = self.run_script_with_input(user_input)
+        self.assertIn("GP (common ratio r = 2)", stdout)
+
+    def test_hp_sequence(self):
+        user_input = "1\n6, 3, 2, 1.5\n2\n"
+        stdout, _ = self.run_script_with_input(user_input)
+        self.assertIn("HP (reciprocal AP difference = 0.166667)", stdout)
+
+    def test_agp_sequence(self):
+        user_input = "1\n2, 8, 24, 64\n2\n"
+        stdout, _ = self.run_script_with_input(user_input)
+        self.assertIn("AGP (repetition ratio r = 2)", stdout)
+
+    def test_non_agp_zero_sequence(self):
+        # Sequence like [0, 1, 0, 0] should not be identified as AGP with ratio 0
+        user_input = "1\n0, 1, 0, 0\n2\n"
+        stdout, _ = self.run_script_with_input(user_input)
+        self.assertNotIn("AGP (repetition ratio r = 0)", stdout)
+        self.assertIn("Not AP, GP, AGP, or HP for the given values", stdout)
+
+    def test_valid_agp_zero_sequence(self):
+        # Sequence like [5, 0, 0, 0] is a valid AGP with ratio 0
+        user_input = "1\n5, 0, 0, 0\n2\n"
+        stdout, _ = self.run_script_with_input(user_input)
+        self.assertIn("AGP (repetition ratio r = 0)", stdout)
+
+if __name__ == "__main__":
+    unittest.main()