Add return on investment to math

algorithms/maths/__init__.py

@@ -26,3 +26,4 @@
 from .magic_number import *
 from .krishnamurthy_number import *
 from .num_perfect_squares import *
+from .return_on_investment import *

algorithms/maths/return_on_investment.py

@@ -0,0 +1,53 @@
+"""
+Return on Investment (ROI)
+
+ROI measures the profitability of an investment relative to its cost,
+expressed as a percentage.
+
+Formula: ROI = (Gain - Cost) / Cost * 100
+
+Reference: https://www.investopedia.com/terms/r/returnoninvestment.asp
+
+Complexity:
+    Time:  O(1)
+    Space: O(1)
+"""
+
+from __future__ import annotations
+
+
+def return_on_investment(
+    gain_from_investment: float, cost_of_investment: float
+) -> float:
+    """
+    Calculate return on investment as a percentage.
+
+    Args:
+        gain_from_investment: Total value gained from the investment.
+        cost_of_investment: Total cost of the investment.
+
+    Returns:
+        ROI as a percentage.
+
+    Raises:
+        ValueError: If cost_of_investment is not positive.
+
+    Examples:
+        >>> return_on_investment(1000.0, 500.0)
+        100.0
+        >>> return_on_investment(500.0, 500.0)
+        0.0
+        >>> return_on_investment(200.0, 500.0)
+        -60.0
+        >>> return_on_investment(0.0, 500.0)
+        -100.0
+        >>> return_on_investment(1000.0, 0.0)
+        Traceback (most recent call last):
+            ...
+        ValueError: cost_of_investment must be greater than 0
+    """
+    if cost_of_investment <= 0:
+        raise ValueError("cost_of_investment must be greater than 0")
+    return round(
+        (gain_from_investment - cost_of_investment) / cost_of_investment * 100, 2
+    )