A-M baby

Task/Knapsack-problem-0-1/Python/knapsack-problem-0-1-1.py

@@ -0,0 +1,31 @@
+from itertools import combinations
+
+def anycomb(items):
+    ' return combinations of any length from the items '
+    return ( comb
+             for r in range(1, len(items)+1)
+             for comb in combinations(items, r)
+             )
+
+def totalvalue(comb):
+    ' Totalise a particular combination of items'
+    totwt = totval = 0
+    for item, wt, val in comb:
+        totwt  += wt
+        totval += val
+    return (totval, -totwt) if totwt <= 400 else (0, 0)
+
+items = (
+    ("map", 9, 150), ("compass", 13, 35), ("water", 153, 200), ("sandwich", 50, 160),
+    ("glucose", 15, 60), ("tin", 68, 45), ("banana", 27, 60), ("apple", 39, 40),
+    ("cheese", 23, 30), ("beer", 52, 10), ("suntan cream", 11, 70), ("camera", 32, 30),
+    ("t-shirt", 24, 15), ("trousers", 48, 10), ("umbrella", 73, 40),
+    ("waterproof trousers", 42, 70), ("waterproof overclothes", 43, 75),
+    ("note-case", 22, 80), ("sunglasses", 7, 20), ("towel", 18, 12),
+    ("socks", 4, 50), ("book", 30, 10),
+    )
+bagged = max( anycomb(items), key=totalvalue) # max val or min wt if values equal
+print("Bagged the following items\n  " +
+      '\n  '.join(sorted(item for item,_,_ in bagged)))
+val, wt = totalvalue(bagged)
+print("for a total value of %i and a total weight of %i" % (val, -wt))

Task/Knapsack-problem-0-1/Python/knapsack-problem-0-1-2.py

@@ -0,0 +1,53 @@
+try:
+    xrange
+except:
+    xrange = range
+
+def totalvalue(comb):
+    ' Totalise a particular combination of items'
+    totwt = totval = 0
+    for item, wt, val in comb:
+        totwt  += wt
+        totval += val
+    return (totval, -totwt) if totwt <= 400 else (0, 0)
+
+items = (
+    ("map", 9, 150), ("compass", 13, 35), ("water", 153, 200), ("sandwich", 50, 160),
+    ("glucose", 15, 60), ("tin", 68, 45), ("banana", 27, 60), ("apple", 39, 40),
+    ("cheese", 23, 30), ("beer", 52, 10), ("suntan cream", 11, 70), ("camera", 32, 30),
+    ("t-shirt", 24, 15), ("trousers", 48, 10), ("umbrella", 73, 40),
+    ("waterproof trousers", 42, 70), ("waterproof overclothes", 43, 75),
+    ("note-case", 22, 80), ("sunglasses", 7, 20), ("towel", 18, 12),
+    ("socks", 4, 50), ("book", 30, 10),
+    )
+
+def knapsack01_dp(items, limit):
+    table = [[0 for w in range(limit + 1)] for j in xrange(len(items) + 1)]
+
+    for j in xrange(1, len(items) + 1):
+        item, wt, val = items[j-1]
+        for w in xrange(1, limit + 1):
+            if wt > w:
+                table[j][w] = table[j-1][w]
+            else:
+                table[j][w] = max(table[j-1][w],
+                                  table[j-1][w-wt] + val)
+
+    result = []
+    w = limit
+    for j in range(len(items), 0, -1):
+        was_added = table[j][w] != table[j-1][w]
+
+        if was_added:
+            item, wt, val = items[j-1]
+            result.append(items[j-1])
+            w -= wt
+
+    return result
+
+
+bagged = knapsack01_dp(items, 400)
+print("Bagged the following items\n  " +
+      '\n  '.join(sorted(item for item,_,_ in bagged)))
+val, wt = totalvalue(bagged)
+print("for a total value of %i and a total weight of %i" % (val, -wt))