Add reverse number pattern implementation

Author: Barnavo Dey

maths/reverse_number_pattern.py

@@ -0,0 +1,38 @@
+"""
+Reverse number pattern.
+
+Example:
+>>> reverse_number_pattern(4)
+['1234', '123', '12', '1']
+"""
+
+from typing import List
+
+
+def reverse_number_pattern(n: int) -> List[str]:
+    """
+    Returns a reverse number pattern.
+
+    >>> reverse_number_pattern(3)
+    ['123', '12', '1']
+    >>> reverse_number_pattern(1)
+    ['1']
+    >>> reverse_number_pattern(0)
+    []
+    """
+    if n <= 0:
+        return []
+
+    result = []
+    for i in range(n, 0, -1):
+        line = ""
+        for x in range(1, i + 1):
+            line += str(x)
+        result.append(line)
+    return result
+
+
+if __name__ == "__main__":
+    import doctest
+    doctest.testmod()
+