Question

I keep getting a TypeError: unsupported operand type for +: ‘int’ and ‘list’
so I guess the array isn’t being indexed? Please assist.

def main():
    arr = [1, 2, 3, 4, 5]
    length = len(arr)
    maxAns = msa2(length, arr)
    print maxAns

def msa2(length, *arr):
    maxThus = 0
    for i in range(0, length):
        sum = 0
        for j in range(i, length):
            sum = sum + arr[j]     # how to get value in index j
            max(maxThus, sum)
    return maxThus

if __name__ == '__main__':
    main()

Answer 1

You should not use *arr; remove the * wildcard character and your code will work.

With the wildcard character, the argument passed into msa2 is seen as one of potentially more extra positional arguments, so arr inside msa2 is a list of those arguments, with the first element being the list you passed in when you called msa2:

>>> def foo(*args):
...     print args
... 
>>> foo(1, 2, 3)
(1, 2, 3)
>>> foo([1, 2, 3])
([1, 2, 3],)

Your function also will always return 0; you do not update maxThus anywhere. You probably meant to assign the result of max(maxThus, sum) to maxThus:

maxThus = max(maxThus, sum)