Python-thing-recursion-wonderings.py

recur_even_odd_list_split.py

l1 = [1,3,9,10,4,3,2,5,17,14,11]

def splitIt(x):
    '''
    This recursive function takes a list of positive integers
    x as argument and returns a tuple of two lists: a list of the even integers
    in x followed by a list of the odd integers in x.

    E.g. x = [3,2,1,5,4,6] gives [1,3,5] [2,4,6]
    x = [1,3,9] gives [1,3,9] []
    '''
    # base case: 1 item in list.
    # if check and generate list with that item, and append this to a new list ([odd],[even])
    even_list = []
    odd_list = []

    splitHelper(x, even_list, odd_list)


    return (even_list, odd_list)

def numberIsEven(x):
    return x % 2 == 0

def splitHelper(x, even_list, odd_list):
    # check to see if position 1 (or list[0]) is even or odd. If even, append to even_list. Else append to odd_list.
    if numberIsEven(x[0]):
        print("item is even" + str(x))
        # add to even list
        even_list.append(x[0])
        print("even list " + str(even_list))
    else:
        print("item is odd" + str(x))
        # add to odd list
        odd_list.append(x[0])
        print("odd list " + str(odd_list))
        
    if len(x) == 1:
        return x
    
    return (splitHelper(x[1:], even_list, odd_list))