Add reverse number pattern (fixes #13976)

maths/reverse_number_pattern.py

@@ -0,0 +1,32 @@
+"""
+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 []
+
+    return ["".join(str(x) for x in range(1, i + 1)) for i in range(n, 0, -1)]
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()