我哪里错了？

Question

Question Write function mssl() (minimum sum sub-list) that takes as input a list of integers.It then computes and returns the sum of the maximum sum sub-list of the input list. The maximum sum sub-list is a sub-list (slice) of the input list whose sum of entries is largest. The empty sub-list is defined to have sum 0. For example, the maximum sum sub-list of the list [4, -2, -8, 5, -2, 7, 7, 2, -6, 5] is [5, -2, 7, 7, 2] and the sum of its entries is 19. l = [4, -2, -8, 5, -2, 7, 7, 2, -6, 5] mssl(l) 19 mssl([3,4,5]) 12 mssl([-2,-3,-5]) 0 In the last example, the maximum sum sub-list is the empty sub-list because all list items are negative. THIS IS MY SOLUTION

 def mssl(lst):
    pos,neg,TotalList=[],[],[]
    for items in range(len(lst)):
         if(lst[items]>0):
            pos+=[lst[items]]
         else:
             neg+=[lst[items]]
    TotalPos=sum(pos)
    TotalNeg=sum(neg)

    if(len(neg)>0):
        for negatives in range(len(neg)):
         TotalList=[TotalPos+neg[negatives]]
        if(TotalList>TotalList[negatives-1]):
               print(TotalList)
    else:
        TotalList=TotalPos
    print(TotalList)

THIS IS NOT A HOMEWORK QUESTION I AM LEARNING PYTHON FOR FUN, PLEASE LET ME KNOW WHERE I AM WRONG

Answer 1

It looks like you're trying to learn programming, with python as your first language. This particular problem is a somewhat difficult one to start with. I would advise you to take a straightforward, brute-force approach at first. Evaluate the sums of all the subsequences, one after another, and keep track of which is largest. Once you have a function that will produce the correct answer, you can look for a better (faster, more elegant, whatever) solution.

As to your code, it really has nothing to do with the question. For example, TotalList is always a one-element list. The expression TotalList[negatives-1] doesn't make much sense; if there's only one element in the list, you can access it as TotalList[0] . The expression TotalList>TotalList[negatives-1] makes no sense at all; you don't want to compare a list to a number.

This is a well-known problem, and a simple, fast solution is not at all easy to come up with, so don't be discouraged if you don't find it. Once you get a straightforward solution, you can think about an elegant one. This problem can be solved in one line of python, using list comprehensions. Trying to do that will lead to improvement in your python style. For example, instead of writing

 for items in range(len(lst)):
         if(lst[items]>0):
            pos+=[lst[items]]
         else:
             neg+=[lst[items]] 

you can, and should write

pos = [x for x in lst if x > 0]
neg = [x for x in lst if x < 0]

Good luck learning python.