Creating an array of numbers that sum to a given number

Question

I\'ve been working on some quick and dirty scripts for doing some of my chemistry homework, and one of them iterates through lists of a constant length where all the element

Answer 1

Generic, recursive solution:

def get_lists_with_sum(length, my_sum):
    if my_sum == 0:
        return [[0 for _ in range(length)]]

    if not length:
        return [[]]
    elif length == 1:
        return [[my_sum]]
    else:
        lists = []
        for i in range(my_sum+1):
            rest = my_sum - i
            sublists = get_lists_with_sum(length-1, rest)
            for sl in sublists:
                sl.insert(0, i)
                lists.append(sl)

    return lists

print get_lists_with_sum(11, 8)