why Python script if statement not working correctly?

Question

I was writing knapsack

w = [0 for x in xrange(item_count+1)]  
v = [0 for x in xrange(item_count+1)]

assigned value and weight (v, w) respectively. created

c = [[0 for x in xrange(capacity+1)] for x in xrange(item_count+1)]

c, w and v is assigned values after this respectively(not zero)

for i in range(1,item_count+1):  
    #for ever possible weight  
    for j in range(0,capacity+1):       
    #can we add this item to this?  
        if w[i] <= j :  
            c[i][j] = max(c[i-1][j], v[i] + c[i-1][j-w[i]])  
        else:  
            c[i][j] = c[i-1][j]

This if w[i] <= j: is always False even if on printing w[i] seems greater than j. Dont know why?

you never assign to w and it is initialized to 0. so is always zero — fabrizioM, Mar 05 '14 at 18:21
Hint: `w = [0 for x in xrange(item_count+1)]` could be written `w = [0] * (item_count + 1)`. Same for the others — Ricardo Cárdenes, Mar 05 '14 at 18:22
actually i forgot to add that after initilizing i assigned value using input from stdin to v and w so its not 0 — ashmish2, Mar 05 '14 at 18:40

score 2 · Answer 1 · answered Mar 05 '14 at 18:23

2

w[i] is always 0 in your code. Never touched after initilization

answered Mar 05 '14 at 18:23

DhruvPathak

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actually i forgot to add that after initilizing i assigned value using input from stdin to v and w – ashmish2 Mar 05 '14 at 18:39

why Python script if statement not working correctly?

1 Answers1