Greedy-Algorithms: Knapsack small code cleanup

Greedy-Algorithms/cs412_knapsack_fractional.py

@@ -9,10 +9,10 @@ Honor Code and Acknowledgments:
 """
 
 from dataclasses import dataclass
-from typing import override
+from typing import Self, override
 
 
-# I don't like tuples
+# I don't like tuples, dataclasses ftw
 @dataclass(frozen=True)
 class KnapsackItem:
     name: str
@@ -20,42 +20,42 @@ class KnapsackItem:
     weight: float
 
     @property
-    def value_per(self) -> float:
+    def value_ratio(self) -> float:
         return self.value / self.weight
 
     @override
     def __str__(self) -> str:
         return f"{self.name}({self.value:.2f}, {self.weight:.2f})"
 
-    @staticmethod
-    def from_str(string: str) -> "KnapsackItem":
-        values: list[str] = string.split()
+    @classmethod
+    def parse(cls, string: str) -> Self:
+        values: list[str] = string.strip().split()
         name, value, weight = values[0], float(values[1]), float(values[2])
-        return KnapsackItem(name, value, weight)
+        return cls(name, value, weight)
 
 
 def knapsack(
     capacity: int, items: list[KnapsackItem]
 ) -> tuple[list[KnapsackItem], float]:
-    cur_capacity: float = capacity
-    sorted_items: list[KnapsackItem] = sorted(items, key=lambda i: -i.value_per)
+
+    current_capacity: float = float(capacity)
+    sorted_items: list[KnapsackItem] = sorted(items, key=lambda i: -i.value_ratio)
 
     total_value: float = 0.0
     fractional_items: list[KnapsackItem] = []
 
     for item in sorted_items:
-        if abs(cur_capacity) < 1e-8:
+        if abs(current_capacity) < 1e-8:
             break
 
-        if cur_capacity < item.weight:
-            value: float = item.value_per * cur_capacity
+        name, value, weight = item.name, item.value, item.weight
+        if current_capacity < weight:
+            value = item.value_ratio * current_capacity
+            weight = current_capacity
+
+        fractional_items.append(KnapsackItem(name, value, weight))
         total_value += value
-            fractional_items.append(KnapsackItem(item.name, value, cur_capacity))
-            cur_capacity = 0
-        else:
-            total_value += item.value
-            fractional_items.append(KnapsackItem(item.name, item.value, item.weight))
-            cur_capacity -= item.weight
+        current_capacity -= weight
 
     return fractional_items, total_value
 
@@ -66,7 +66,7 @@ def main():
     capacity: int = int(input())
     n: int = int(input())
 
-    items: list[KnapsackItem] = [KnapsackItem.from_str(input()) for _ in range(0, n)]
+    items: list[KnapsackItem] = [KnapsackItem.parse(input()) for _ in range(0, n)]
 
     fractional_items, total_value = knapsack(capacity, items)