# my knapsack code does not work in python 3 can anyone help what is the problem with my code?

``````def knapSack(W, wi, pi, i):

if i == 0 or W == 0:
return 0

if (wi[i-1] > W):
return knapSack(W, wi, pi, i-1)

else:
return max(
pi[n-1] + knapSack(
W-wi[n-1], wi, pi, n-1),
knapSack(W, wi, pi, n-1))

pi = [25, 5, 20, 120, 100, 0, 30, 0, 0, 75, 100]
wi = [2, 4, 1, 8, 10, 5, 3, 7, 6, 12, 7]
W = 30
n = len(pi)
knapSack(W, wi, pi, n)
``````

I expect the answer of function at the end but I keep getting errors .
I get (maximum recursion depth exceeded)error but I don’t think it’s the problem .

### >Solution :

The `knappSack()` function is given the parameter `i` but in the function you are still using `n`, which will stay the same in the recursions. Changing to

``````def knapSack(W, wi, pi, i):

if i == 0 or W == 0:
return 0

if (wi[i-1] > W):
return knapSack(W, wi, pi, i-1)

else:
return max(
pi[i-1] + knapSack(W-wi[i-1], wi, pi, i-1),
knapSack(W, wi, pi, i-1))

pi = [25, 5, 20, 120, 100, 0, 30, 0, 0, 75, 100]
wi = [2, 4, 1, 8, 10, 5, 3, 7, 6, 12, 7]
W = 30
n = len(pi)
knapSack(W, wi, pi, n)
``````

should solve the issue.