MaxValueSelect() function has some errors . any fixes?

Question

My code is:

def maxValueSelection(items,V):
maxval = 0
val = 0
sorted_dict={}
for i in items.items():
  sorted_dict[i[1][1]] = [i[1][0],i[0]]
sorted_dict_list = (sorted(sorted_dict))[::-1]
while sorted_dict_list!=[]:
  item = sorted_dict_list[0]
  if(sorted_dict[item][0] + val<=V):
    maxval+=item
    val = val+sorted_dict[item][0]
  sorted_dict_list.pop(0)
return maxval


items = {1:(4,400),2:(9,1800),3:(10,3500),4:(20,4000),5:(2,1000),6:(1,200)}
V = 20

print(maxValueSelection(items,V))

I have used a greedy algorithm for the question in which I have two values which records the value of the item and one monitors the weight of the items which should not be exceeded more than a threshold value mentioned in the question. It seems like my greedy strategy is working upto some extent but nearly misses the maxValue in every test case. It will be helpful if someone tells me how to fix this issue with my code

FYI the [ask] page explains why your prompt and example input/output should be in text form, not an image. — Random Davis, Dec 02 '21 at 16:07
You need also to explain what output you except with some inputs. — Ptit Xav, Dec 02 '21 at 16:11

score 0 · Answer 1 · answered Dec 02 '21 at 16:44

0

If I understood correctly what you need. this code selects V elements from the dict items, with maximum total value.

from operator import itemgetter, truediv
def maxValueSelection(items,V):
    maxval = 0
    val = 0
    itemlist = sorted([i[1] for i in items.items()],key=itemgetter(1),reverse=True)
    for item in itemlist:
        if V > 0:
            val = item[1]
            maxval += val * min(V,item[0])
            V -= min(V,item[0])
    return maxval
items = {1:(4,400),2:(9,1800),3:(10,3500),4:(20,4000),5:(2,1000),6:(1,200)}
V = 20
print(maxValueSelection(items,V))

answered Dec 02 '21 at 16:44

Chedy Benmoussa

5
4

No Dude. This gives the wrong output. – Maheedhar A Dec 03 '21 at 05:14
I will add the test cases here. Test case#1 items = {1:(10,60),2:(20,100),3:(30,120)}, V =50. Expected o/p: 240. Test case #2 items = {1:(4,400),2:(9,1800),3:(10,3500),4:(5,4000),5:(2,1000),6:(1,200)}, V = 15 , Expected output = 7800 – Maheedhar A Dec 03 '21 at 05:17
can you explain how you got 240 in the first example – Chedy Benmoussa Dec 03 '21 at 14:02
Its like item 3 with weight 3 and 2x item 1 with weight 10 – Maheedhar A Dec 05 '21 at 00:48
if i can pass the weight available then why not 5* item1 = 300 ?! – Chedy Benmoussa Dec 06 '21 at 11:05

MaxValueSelect() function has some errors . any fixes?

1 Answers1