numbers_in_lists.py

# Numbers in lists. Exercise from Udacity course.
# define a procedure that takes in a string of numbers from 1-9 and
# outputs a list with the following parameters:
# Every number in the string should be inserted into the list.
# If a number x in the string is less than or equal 
# to the preceding number y, the number x should be inserted 
# into a sublist. Continue adding the following numbers to the 
# sublist until reaching a number z that
# is greater than the number y. 
# Then add this number z to the normal list and continue.

def numbers_in_lists(string):
    result = []
    temp = []
    for i in range(len(string)):
        if not result:
            result.append(int(string[i]))
            continue

        if int(string[i]) <= result[-1]:
            temp.append(int(string[i]))
        else:
            if temp:
                result.append(temp)
                temp = []  
            result.append(int(string[i]))
    if temp:
        result.append(temp)

    return result



def main():
    string = '543987'
    result = [5,[4,3],9,[8,7]]
    print(repr(string), numbers_in_lists(string) == result)
    
    string= '987654321'
    result = [9,[8,7,6,5,4,3,2,1]]
    print(repr(string), numbers_in_lists(string) == result)

    string = '455532123266'
    result = [4, 5, [5, 5, 3, 2, 1, 2, 3, 2], 6, [6]]
    print(repr(string), numbers_in_lists(string) == result)

    string = '123456789'
    result = [1, 2, 3, 4, 5, 6, 7, 8, 9]
    print(repr(string), numbers_in_lists(string) == result)


if __name__ == '__main__':
    main()