# Advent of Code 2017¶

## December 4th¶

To ensure security, a valid passphrase must contain no duplicate words.

For example:

- aa bb cc dd ee is valid.
- aa bb cc dd aa is not valid - the word aa appears more than once.
- aa bb cc dd aaa is valid - aa and aaa count as different words.

The system's full passphrase list is available as your puzzle input. How many passphrases are valid?

In [1]:

    from notebook_preamble import J, V, define

I'll assume the input is a Joy sequence of sequences of integers.

    [[5 1 9 5]
     [7 5 4 3]
     [2 4 6 8]]

So, obviously, the initial form will be a `step` function:

    AoC2017.4 == 0 swap [F +] step

    F == [size] [unique size] cleave =

The `step_zero` combinator includes the `0 swap` that would normally open one of these definitions:

In [2]:

    J('[step_zero] help')

    ==== Help on step_zero ====

    0 roll> step

    ---- end (step_zero)

    AoC2017.4 == [F +] step_zero

In [3]:

    define('AoC2017.4 [[size] [unique size] cleave = +] step_zero')

In [4]:

    J('''

    [[5 1 9 5]
     [7 5 4 3]
     [2 4 6 8]] AoC2017.4

    ''')

    2