add camping

chapter11/camping.py

@@ -0,0 +1,85 @@
+import logging
+from dataclasses import dataclass
+
+from tabulate import tabulate
+
+logging.basicConfig(
+    level=logging.DEBUG,
+    format="%(asctime)s %(levelname)s\n\r%(message)s",
+    datefmt="%H:%M:%S",
+)
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class Item:
+    name: str
+    priority: int
+    weight: int
+
+
+def dynamic(items, n):
+    # create table and zero fill it (required for calculations)
+    table = [[0 for _ in range(W + 1)] for _ in range(n + 1)]
+
+    # calculate all possible max values for items in knapsack
+    for i in range(1, n + 1):
+        for w in range(1, W + 1):
+            if items[i - 1].weight <= w:
+                table[i][w] = max(
+                    items[i - 1].priority + table[i - 1][w - items[i - 1].weight],
+                    table[i - 1][w],
+                )
+            else:
+                table[i][w] = table[i - 1][w]
+
+    format_and_print(table)
+
+    return get_items_in_knapsack(table[-1][-1], items, n, table)
+
+
+def format_and_print(table):
+    # enumerate first row (headings) + label each row in column0
+    for i, row in enumerate(table):
+        if i == 0:
+            continue
+        row[0] = items[i - 1].name
+    table[0] = [i for i in range(W + 1)]
+    table[0][0] = None
+
+    # print tabularised 2D array
+    logger.info([item.name for item in items])
+    logger.info(tabulate(table, tablefmt="pretty"))
+
+
+def get_items_in_knapsack(highest_value, items, n, table):
+    in_knapsack = []
+
+    w = W
+    res = highest_value
+    for i in range(n, 0, -1):
+        if res <= 0:
+            break
+
+        if res == table[i - 1][w]:
+            continue
+        else:
+            in_knapsack.append(items[i - 1].name)
+
+            res = res - items[i - 1].priority
+            w = w - items[i - 1].weight
+
+    return in_knapsack
+
+
+items = [
+    Item("Water", 10, 3),
+    Item("Book", 3, 1),
+    Item("Food", 9, 2),
+    Item("Jacket", 5, 2),
+    Item("Camera", 6, 1),
+]
+W = 6
+in_knapsack = dynamic(items, len(items))
+
+print(f"Knapsack contains: {in_knapsack}")