From 9111d75db7ff221c55ddb56f46f4ec5e83480a80 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 10:34:32 +0530
Subject: [PATCH 01/16] Create fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 100 +++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 greedy_methods/fractional_cover_problem.py

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
new file mode 100644
index 000000000000..4e578a6435db
--- /dev/null
+++ b/greedy_methods/fractional_cover_problem.py
@@ -0,0 +1,100 @@
+# Explanation:- https://en.wikipedia.org/wiki/Set_cover_problem
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Item:
+    weight: int
+    value: int
+
+    def __eq__(self, other):
+        return self.weight == other.weight and self.value == other.value
+
+
+def fractional_cover(items: list[Item], capacity: int) -> float:
+    """
+    Solve the Fractional Cover Problem.
+
+    Args:
+        items (List[Item]): A list of items, where each item is represented as an
+            Item object with weight and value attributes.
+        capacity (int): The maximum weight capacity of the knapsack.
+
+    Returns:
+        float: The maximum value that can be obtained by selecting fractions of items to
+        cover the knapsack's capacity.
+
+    Examples:
+    >>> items = [Item(10, 60), Item(20, 100), Item(30, 120)]
+    >>> fractional_cover(items, 50)
+    240.0
+
+    >>> items = [Item(20, 100), Item(30, 120), Item(10, 60)]
+    >>> fractional_cover(items, 25)
+    135.0
+
+    >>> items = [Item(10, 60), Item(20, 100), Item(30, 120)]
+    >>> fractional_cover(items, 60)
+    280.0
+
+    >>> items = [Item(5, 30), Item(10, 60), Item(15, 90)]
+    >>> fractional_cover(items, 30)
+    180.0
+
+    >>> items = []
+    >>> fractional_cover(items, 50)
+    0.0
+
+    >>> items = [Item(10, 60)]
+    >>> fractional_cover(items, 5)
+    30.0
+
+    >>> items = [Item(10, 60)]
+    >>> fractional_cover(items, 1)
+    6.0
+
+    >>> items = [Item(1, 1)]
+    >>> fractional_cover(items, 0)
+    0.0
+
+    >>> items = [Item(1, 1)]
+    >>> fractional_cover(items, 1)
+    1.0
+
+    >>> items = [Item(1, 1)]
+    >>> fractional_cover(items, 2)
+    1.0
+
+    >>> items = [Item(1, 1)]
+    >>> fractional_cover(items, 0)
+    0.0
+    """
+    # Calculate the value-to-weight ratios for each item
+    ratios = [(item.value / item.weight, item) for item in items]
+
+    # Sort the items by their value-to-weight ratio in descending order
+    ratios.sort(key=lambda x: x[0], reverse=True)
+
+    total_value = 0.0
+    remaining_capacity = capacity
+
+    for ratio, item in ratios:
+        if remaining_capacity == 0:
+            break
+
+        weight_taken = min(item.weight, remaining_capacity)
+        total_value += weight_taken * ratio
+        remaining_capacity -= weight_taken
+
+    return total_value
+
+
+if __name__ == "__main__":
+    import doctest
+
+    result = doctest.testmod().failed
+    if result == 0:
+        print("All tests passed")
+    else:
+        print(f"{result} test(s) failed")

From 18b625fe7d5fd24138e2ff84ebeaf860771716a6 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 10:44:32 +0530
Subject: [PATCH 02/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 26 +++++++++-------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 4e578a6435db..03d9f404a102 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,7 +8,16 @@ class Item:
     weight: int
     value: int
 
-    def __eq__(self, other):
+    def __eq__(self, other: 'Item') -> bool:
+        """
+        Compare two Item objects for equality based on weight and value attributes.
+
+        Args:
+            other (Item): Another Item object to compare with.
+
+        Returns:
+            bool: True if the objects are equal, False otherwise.
+        """
         return self.weight == other.weight and self.value == other.value
 
 
@@ -54,18 +63,6 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
     >>> fractional_cover(items, 1)
     6.0
 
-    >>> items = [Item(1, 1)]
-    >>> fractional_cover(items, 0)
-    0.0
-
-    >>> items = [Item(1, 1)]
-    >>> fractional_cover(items, 1)
-    1.0
-
-    >>> items = [Item(1, 1)]
-    >>> fractional_cover(items, 2)
-    1.0
-
     >>> items = [Item(1, 1)]
     >>> fractional_cover(items, 0)
     0.0
@@ -74,7 +71,7 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
     ratios = [(item.value / item.weight, item) for item in items]
 
     # Sort the items by their value-to-weight ratio in descending order
-    ratios.sort(key=lambda x: x[0], reverse=True)
+    ratios.sort(key=lambda item_ratio: item_ratio[0], reverse=True)
 
     total_value = 0.0
     remaining_capacity = capacity
@@ -89,7 +86,6 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
 
     return total_value
 
-
 if __name__ == "__main__":
     import doctest
 

From 64e32b3a1d8da0e2e57f7fa961554522a7dbb4cd Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 7 Oct 2023 05:15:05 +0000
Subject: [PATCH 03/16] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 greedy_methods/fractional_cover_problem.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 03d9f404a102..f9c565bb8ffe 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,7 +8,7 @@ class Item:
     weight: int
     value: int
 
-    def __eq__(self, other: 'Item') -> bool:
+    def __eq__(self, other: "Item") -> bool:
         """
         Compare two Item objects for equality based on weight and value attributes.
 
@@ -86,6 +86,7 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
 
     return total_value
 
+
 if __name__ == "__main__":
     import doctest
 

From 3436d206a585f7f7920ee2f3e8cf425b1cf6a490 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 10:48:18 +0530
Subject: [PATCH 04/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index f9c565bb8ffe..4fd71ee6c83a 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -17,6 +17,15 @@ def __eq__(self, other: "Item") -> bool:
 
         Returns:
             bool: True if the objects are equal, False otherwise.
+
+        Examples:
+        >>> item1 = Item(10, 60)
+        >>> item2 = Item(10, 60)
+        >>> item3 = Item(20, 100)
+        >>> item1 == item2
+        True
+        >>> item1 == item3
+        False
         """
         return self.weight == other.weight and self.value == other.value
 
@@ -95,3 +104,4 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
         print("All tests passed")
     else:
         print(f"{result} test(s) failed")
+    

From 0d3bbfb99b28f4038c422757ef8a1bfcd69a6f15 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 7 Oct 2023 05:18:51 +0000
Subject: [PATCH 05/16] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 greedy_methods/fractional_cover_problem.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 4fd71ee6c83a..026636e07095 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -104,4 +104,3 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
         print("All tests passed")
     else:
         print(f"{result} test(s) failed")
-    

From 32b02e3c042d81027d3aebf1fe6581a6f90b3912 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 10:57:13 +0530
Subject: [PATCH 06/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 026636e07095..11372baada1d 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -27,6 +27,8 @@ def __eq__(self, other: "Item") -> bool:
         >>> item1 == item3
         False
         """
+        if not isinstance(other, Item):
+            return NotImplemented
         return self.weight == other.weight and self.value == other.value
 
 

From 31017cacb1da90cf2e36060e31ac1cab55d4f9d7 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 11:07:39 +0530
Subject: [PATCH 07/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 11372baada1d..8e8fc7df6457 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,12 +8,12 @@ class Item:
     weight: int
     value: int
 
-    def __eq__(self, other: "Item") -> bool:
+    def __eq__(self, other: object) -> bool:
         """
         Compare two Item objects for equality based on weight and value attributes.
 
         Args:
-            other (Item): Another Item object to compare with.
+            other (object): Another object to compare with.
 
         Returns:
             bool: True if the objects are equal, False otherwise.
@@ -28,7 +28,7 @@ def __eq__(self, other: "Item") -> bool:
         False
         """
         if not isinstance(other, Item):
-            return NotImplemented
+            return False  # Return False for non-Item objects
         return self.weight == other.weight and self.value == other.value
 
 
@@ -106,3 +106,4 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
         print("All tests passed")
     else:
         print(f"{result} test(s) failed")
+        

From 184b146017905905380bec73d65e4fb75c3126b3 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 7 Oct 2023 05:38:11 +0000
Subject: [PATCH 08/16] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 greedy_methods/fractional_cover_problem.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 8e8fc7df6457..410af2cf6726 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -106,4 +106,3 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
         print("All tests passed")
     else:
         print(f"{result} test(s) failed")
-        

From 1d3821601fae35c38f74db32a10706532f4ee9f0 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 11:09:27 +0530
Subject: [PATCH 09/16] Update fractional_cover_problem.py


From 32b219f09d65e4dd9992922854a967357bb607c7 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 12:28:47 +0530
Subject: [PATCH 10/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 23 +---------------------
 1 file changed, 1 insertion(+), 22 deletions(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 410af2cf6726..eca262da37ed 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,30 +8,9 @@ class Item:
     weight: int
     value: int
 
-    def __eq__(self, other: object) -> bool:
-        """
-        Compare two Item objects for equality based on weight and value attributes.
-
-        Args:
-            other (object): Another object to compare with.
-
-        Returns:
-            bool: True if the objects are equal, False otherwise.
-
-        Examples:
-        >>> item1 = Item(10, 60)
-        >>> item2 = Item(10, 60)
-        >>> item3 = Item(20, 100)
-        >>> item1 == item2
-        True
-        >>> item1 == item3
-        False
-        """
-        if not isinstance(other, Item):
-            return False  # Return False for non-Item objects
+    def not_really__eq__(self, other: object) -> bool:
         return self.weight == other.weight and self.value == other.value
 
-
 def fractional_cover(items: list[Item], capacity: int) -> float:
     """
     Solve the Fractional Cover Problem.

From cf108baed48c79a37fdf6c8d2b023d7715e9f6a8 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 7 Oct 2023 06:59:19 +0000
Subject: [PATCH 11/16] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 greedy_methods/fractional_cover_problem.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index eca262da37ed..9690cccc7697 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -11,6 +11,7 @@ class Item:
     def not_really__eq__(self, other: object) -> bool:
         return self.weight == other.weight and self.value == other.value
 
+
 def fractional_cover(items: list[Item], capacity: int) -> float:
     """
     Solve the Fractional Cover Problem.

From 3c80327f664d873fef6451be94b62025d5f0c8b7 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 12:34:19 +0530
Subject: [PATCH 12/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 9690cccc7697..74c9433459bd 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,7 +8,7 @@ class Item:
     weight: int
     value: int
 
-    def not_really__eq__(self, other: object) -> bool:
+    def __eq__(self, other: 'Item') -> bool:
         return self.weight == other.weight and self.value == other.value
 
 

From a81fa7bd918814dd9966dc5791c1de526b61d702 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 7 Oct 2023 07:04:51 +0000
Subject: [PATCH 13/16] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 greedy_methods/fractional_cover_problem.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 74c9433459bd..1b0be758fd88 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,7 +8,7 @@ class Item:
     weight: int
     value: int
 
-    def __eq__(self, other: 'Item') -> bool:
+    def __eq__(self, other: "Item") -> bool:
         return self.weight == other.weight and self.value == other.value
 
 

From 60d5b767d9fdf672f42ba0ba467361a87bab9ddc Mon Sep 17 00:00:00 2001
From: Christian Clauss <cclauss@me.com>
Date: Sat, 7 Oct 2023 09:09:55 +0200
Subject: [PATCH 14/16] Lose __eq__()

---
 greedy_methods/fractional_cover_problem.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 1b0be758fd88..39045834fa22 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -8,9 +8,6 @@ class Item:
     weight: int
     value: int
 
-    def __eq__(self, other: "Item") -> bool:
-        return self.weight == other.weight and self.value == other.value
-
 
 def fractional_cover(items: list[Item], capacity: int) -> float:
     """

From 503c3bd14ad922de298813092aaec036d5269f58 Mon Sep 17 00:00:00 2001
From: Pronay Debnath <pronayd4455@gmail.com>
Date: Sat, 7 Oct 2023 20:48:01 +0530
Subject: [PATCH 15/16] Update fractional_cover_problem.py

---
 greedy_methods/fractional_cover_problem.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 39045834fa22..1c9762ca3217 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -22,6 +22,9 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
         float: The maximum value that can be obtained by selecting fractions of items to
         cover the knapsack's capacity.
 
+    Raises:
+        ValueError: If the `capacity` is negative.
+
     Examples:
     >>> items = [Item(10, 60), Item(20, 100), Item(30, 120)]
     >>> fractional_cover(items, 50)
@@ -54,7 +57,15 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
     >>> items = [Item(1, 1)]
     >>> fractional_cover(items, 0)
     0.0
+
+    >>> items = [Item(10, 60)]
+    >>> fractional_cover(items, -1)
+    Traceback (most recent call last):
+        ...
+    ValueError: Capacity cannot be negative
     """
+    if capacity < 0:
+        raise ValueError("Capacity cannot be negative")
     # Calculate the value-to-weight ratios for each item
     ratios = [(item.value / item.weight, item) for item in items]
 

From b000f15c23ee47c0ab94294e13f0394bcc657dce Mon Sep 17 00:00:00 2001
From: Christian Clauss <cclauss@me.com>
Date: Sat, 7 Oct 2023 17:46:14 +0200
Subject: [PATCH 16/16] Define Item property ratio

---
 greedy_methods/fractional_cover_problem.py | 78 ++++++++++++----------
 1 file changed, 42 insertions(+), 36 deletions(-)

diff --git a/greedy_methods/fractional_cover_problem.py b/greedy_methods/fractional_cover_problem.py
index 1c9762ca3217..e37c363f1db9 100644
--- a/greedy_methods/fractional_cover_problem.py
+++ b/greedy_methods/fractional_cover_problem.py
@@ -1,6 +1,7 @@
-# Explanation:- https://en.wikipedia.org/wiki/Set_cover_problem
+# https://en.wikipedia.org/wiki/Set_cover_problem
 
 from dataclasses import dataclass
+from operator import attrgetter
 
 
 @dataclass
@@ -8,79 +9,85 @@ class Item:
     weight: int
     value: int
 
+    @property
+    def ratio(self) -> float:
+        """
+        Return the value-to-weight ratio for the item.
+
+        Returns:
+            float: The value-to-weight ratio for the item.
+
+        Examples:
+        >>> Item(10, 65).ratio
+        6.5
+
+        >>> Item(20, 100).ratio
+        5.0
+
+        >>> Item(30, 120).ratio
+        4.0
+        """
+        return self.value / self.weight
+
 
 def fractional_cover(items: list[Item], capacity: int) -> float:
     """
     Solve the Fractional Cover Problem.
 
     Args:
-        items (List[Item]): A list of items, where each item is represented as an
-            Item object with weight and value attributes.
-        capacity (int): The maximum weight capacity of the knapsack.
+        items: A list of items, where each item has weight and value attributes.
+        capacity: The maximum weight capacity of the knapsack.
 
     Returns:
-        float: The maximum value that can be obtained by selecting fractions of items to
-        cover the knapsack's capacity.
+        The maximum value that can be obtained by selecting fractions of items to cover
+        the knapsack's capacity.
 
     Raises:
-        ValueError: If the `capacity` is negative.
+        ValueError: If capacity is negative.
 
     Examples:
-    >>> items = [Item(10, 60), Item(20, 100), Item(30, 120)]
-    >>> fractional_cover(items, 50)
+    >>> fractional_cover((Item(10, 60), Item(20, 100), Item(30, 120)), capacity=50)
     240.0
 
-    >>> items = [Item(20, 100), Item(30, 120), Item(10, 60)]
-    >>> fractional_cover(items, 25)
+    >>> fractional_cover([Item(20, 100), Item(30, 120), Item(10, 60)], capacity=25)
     135.0
 
-    >>> items = [Item(10, 60), Item(20, 100), Item(30, 120)]
-    >>> fractional_cover(items, 60)
+    >>> fractional_cover([Item(10, 60), Item(20, 100), Item(30, 120)], capacity=60)
     280.0
 
-    >>> items = [Item(5, 30), Item(10, 60), Item(15, 90)]
-    >>> fractional_cover(items, 30)
+    >>> fractional_cover(items=[Item(5, 30), Item(10, 60), Item(15, 90)], capacity=30)
     180.0
 
-    >>> items = []
-    >>> fractional_cover(items, 50)
+    >>> fractional_cover(items=[], capacity=50)
     0.0
 
-    >>> items = [Item(10, 60)]
-    >>> fractional_cover(items, 5)
+    >>> fractional_cover(items=[Item(10, 60)], capacity=5)
     30.0
 
-    >>> items = [Item(10, 60)]
-    >>> fractional_cover(items, 1)
+    >>> fractional_cover(items=[Item(10, 60)], capacity=1)
     6.0
 
-    >>> items = [Item(1, 1)]
-    >>> fractional_cover(items, 0)
+    >>> fractional_cover(items=[Item(10, 60)], capacity=0)
     0.0
 
-    >>> items = [Item(10, 60)]
-    >>> fractional_cover(items, -1)
+    >>> fractional_cover(items=[Item(10, 60)], capacity=-1)
     Traceback (most recent call last):
         ...
     ValueError: Capacity cannot be negative
     """
     if capacity < 0:
         raise ValueError("Capacity cannot be negative")
-    # Calculate the value-to-weight ratios for each item
-    ratios = [(item.value / item.weight, item) for item in items]
-
-    # Sort the items by their value-to-weight ratio in descending order
-    ratios.sort(key=lambda item_ratio: item_ratio[0], reverse=True)
 
     total_value = 0.0
     remaining_capacity = capacity
 
-    for ratio, item in ratios:
+    # Sort the items by their value-to-weight ratio in descending order
+    for item in sorted(items, key=attrgetter("ratio"), reverse=True):
         if remaining_capacity == 0:
             break
 
         weight_taken = min(item.weight, remaining_capacity)
-        total_value += weight_taken * ratio
+        total_value += weight_taken * item.ratio
         remaining_capacity -= weight_taken
 
     return total_value
@@ -89,8 +96,7 @@ def fractional_cover(items: list[Item], capacity: int) -> float:
 if __name__ == "__main__":
     import doctest
 
-    result = doctest.testmod().failed
-    if result == 0:
-        print("All tests passed")
-    else:
+    if result := doctest.testmod().failed:
         print(f"{result} test(s) failed")
+    else:
+        print("All tests passed")