1 files changed, 75 insertions, 0 deletions
diff --git a/challenge-287/lubos-kolouch/python/ch-2.py b/challenge-287/lubos-kolouch/python/ch-2.py
new file mode 100644
index 0000000000..f302b7360a
--- /dev/null
+++ b/challenge-287/lubos-kolouch/python/ch-2.py
@@ -0,0 +1,75 @@
+import re
+from typing import Any
+import unittest
+
+
+def is_valid_number(s: str) -> bool:
+    """
+    Determines if the given string is a valid number based on specific rules.
+
+    A valid number is defined as:
+    - An integer number followed by an optional exponent.
+    - A decimal number followed by an optional exponent.
+
+    An integer number is defined with an optional sign '-' or '+' followed by digits.
+
+    Decimal Number:
+    - An optional sign '-' or '+' followed by one of the following:
+        - Digits followed by a dot '.'.
+        - Digits followed by a dot '.' followed by digits.
+        - A dot '.' followed by digits.
+
+    Exponent:
+    - An exponent is defined with an exponent notation 'e' or 'E' followed by an integer number.
+
+    Args:
+        s (str): The input string.
+
+    Returns:
+        bool: True if the string is a valid number, False otherwise.
+    """
+    pattern = r"""
+        ^                       # Start of string
+        [+-]?                   # Optional sign
+        (
+            (                   # Decimal numbers
+                \d+\.\d*        # Digits followed by dot and optional digits
+                |
+                \.\d+           # Dot followed by digits
+                |
+                \d+\.           # Digits followed by dot
+            )
+            |
+            \d+                 # Integer numbers
+        )
+        ([eE][+-]?\d+)?         # Optional exponent
+        $                       # End of string
+    """
+    regex = re.compile(pattern, re.VERBOSE)
+    return bool(regex.match(s))
+
+
+# Unit Tests
+class TestValidNumber(unittest.TestCase):
+
+    def test_examples(self):
+        self.assertEqual(is_valid_number("1"), True, 'Example 1')
+        self.assertEqual(is_valid_number("a"), False, 'Example 2')
+        self.assertEqual(is_valid_number("."), False, 'Example 3')
+        self.assertEqual(is_valid_number("1.2e4.2"), False, 'Example 4')
+        self.assertEqual(is_valid_number("-1."), True, 'Example 5')
+        self.assertEqual(is_valid_number("+1E-8"), True, 'Example 6')
+        self.assertEqual(is_valid_number(".44"), True, 'Example 7')
+
+    def test_additional(self):
+        self.assertEqual(is_valid_number("6e6.5"), False,
+                         'Exponent with decimal')
+        self.assertEqual(is_valid_number(""), False, 'Empty string')
+        self.assertEqual(is_valid_number("123"), True, 'Integer number')
+        self.assertEqual(is_valid_number("-."), False,
+                         'Negative dot without digits')
+        self.assertEqual(is_valid_number("1e"), False, 'Incomplete exponent')
+
+
+if __name__ == "__main__":
+    unittest.main()