max sum of consecutive digits in a number

Question

i need to write a function that adds up consecutive digits in a number and returns the biggest sum of them. i wrote a function that receives to arguments, (m,t). m- stands for the number(int), and t (int also) stands for the numbers of consecutive digits to sum. now i want it to go through all the digits in the number and at the end to return me the max. i dont figure out why my code doesnt work:

def sum_digits(m, t):
    str_m= str(m)

    for i in range(len(str_m)):
        if t+i<len(str_m):
            num= str_n[i:t+i]
            num1='+'.join(num)
            num2= str(eval(num1))
            lst= list(num2)
        else:
            break


return max (lst)

Answer 1

The reason yours doesn't work is that lst is getting reset every iteration. I think you intended to set it at the beginning and add to it each iteration. Also:

Ahhhh!!!! You don't need eval !

def max_sum(m, t):
    digits = map(int, str(m))
    max_sum = cur_sum = sum(digits[:t])
    for i, x in enumerate(s[t:], t):
        cur_sum += x - digits[i - t]
        max_sum = max(max_sum, cur_sum)
    return max_sum

Also, this has O(log m) running time (or O(n) if n is the number of digits in m), rather than the naive O(t * log m) (or O(t * n)).

Answer 2

>>> def maxSum(m, t):
...   m = str(m)
...   answer = 0
...   for digits in (m[i:i+t] for i in range(len(m)-t+1)):
...     answer = max(answer, sum(int(d) for d in digits))
...   return answer
... 
>>> maxSum(1234567, 3)
18