pop removes a value from the list so each time you use pop the length of your list gets shorter and right now you keep deleting numbers from your list using this algorithm.

def sum_two_smallest_numbers(numbers):
    a = 2147483647
    numers = numbers
    b = a
    ind = -1
    for i in range(0, len(numbers)):
#        print(numbers[i])
        if numbers[i] < a and numbers[i] > 0:
            a = numbers[i]
            ind = i
    numbers.pop(ind)
    for j in range(0, len(numbers)-1):
        if numers[j] < b and numers[j] > 0:
            b = numers[j]
    return a + b


print(sum_two_smallest_numbers([19, 5, 42, 2, 77]))

Note that this algorithm assumes there are at least 2 positive numbers in your list. Also, there are more efficient ways to do this with only one for loop.

This works.

a = [-1, 2, 34, 22, 4]
a = [i for i in a if i > 0]

first_min = min(a)
a.remove(first_min)
second_min = min(a)

print(first_min+second_min)

First the rule is never modify a list while iterating on it. You are trying to circumvent it by using indices, but you compute the range before starting the loop and then remove elements from the list => at a time you get an index that is greater or equal than the size of the list.

In addition, you will remove more elements than the smallest one. Let us assume that we fixed the above error and see what happens

• first iteration: 19 is less than 2147483647: a = 19 and 19 is removed from the list
• next: 5 is less that 19: again a = 5 and 5 is removed which is bad because it is the second smallest element !

So you should at least change your algo to only remove the final smallest element:

def sum_two_smallest_numbers(numbers):
    a = 2147483647
    numers = numbers
    b = a
    for i in range(0, len(numbers)):
        print(numbers[i])
        if numbers[i] < a and numbers[i] > 0:
            a = numbers[i]
    numbers.remove(a)
    for j in range(0, len(numers)):
        if numers[j] < b and numers[j] > 0:
            b = numers[j]
    numers.remove(b)
    return a + b

print(sum_two_smallest_numbers([19, 5, 42, 2, 77]))

But this is un-pythonic because Python lists are iterable, and not efficient because you iterate the array twice. This would be better:

def sum_two_smallest_numbers(numbers):
    a = b = 2147483647            # a and b will be the 2 smallest elements
    for i in numbers:
        print(i)
        if i < b:                 # if i >= b : nothing to do
            if i < a:             # new element is the current smallest
                b = a
                a = i
            else:                 # new element is the current second smallest
                b = i
    # uncomment both following line if you want to remove the elements from the array
    #  as a side effect
    # numbers.remove(a)
    # numbers.remove(b)
    return a + b