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Python implementation of the knapsack problem.

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jrtechs 5 years ago
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"""
Jeffery Russell
12-1-18
"""
def knapsack(V, W, capacity):
"""
Dynamic programming implementation of the knapsack problem
:param V: List of the values
:param W: List of weights
:param capacity: max capacity of knapsack
:return: List of tuples of objects stolen in form (w, v)
"""
choices = [[[] for i in range(capacity + 1)] for j in range(len(V) + 1)]
cost = [[0 for i in range(capacity + 1)] for j in range(len(V) + 1)]
for i in range(0, len(V)):
for j in range(0, capacity + 1):
if W[i] > j: # don't include another item
cost[i][j] = cost[i -1][j]
choices[i][j] = choices[i - 1][j]
else: # Adding another item
cost[i][j] = max(cost[i-1][j], cost[i-1][j - W[i]] + V[i])
if cost[i][j] != cost[i-1][j]:
choices[i][j] = choices[i - 1][j - W[i]] + [(W[i], V[i])]
else:
choices[i][j] = choices[i - 1][j]
return choices[len(V) -1][capacity]
def printSolution(S):
"""
Takes the output of knapsack and prints it in a
pretty format.
:param S: list of tuples representing items stolen
:return: None
"""
print("Thief Took:")
for i in S:
print("Weight: " + str(i[0]) + "\tValue: \t" + str(i[1]))
print()
print("Total Value Stolen: " + str(sum(int(v[0]) for v in S)))
print("Total Weight in knapsack: " + str(sum(int(v[1]) for v in S)))
values = [99,1,1,1,1, 1,1]
weights = [5,1,2,3,4,5,1]
printSolution(knapsack(values, weights, 6))

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