Advent of Code 2017

In [1]:

    

from notebook_preamble import D, J, V, define


    

In [2]:

    

J('[0 2 7 0] dup max')


    

    




[0 2 7 0] 7

In [3]:

    

from joy.library import SimpleFunctionWrapper
from joy.utils.stack import list_to_stack


@SimpleFunctionWrapper
def index_of(stack):
    '''Given a sequence and a item, return the index of the item, or -1 if not found.

    E.g.:

       [a b c] a index_of
    ------------------------
               0

       [a b c] d index_of
    ------------------------
            -1

    '''
    item, (sequence, stack) = stack
    i = 0
    while sequence:
        term, sequence = sequence
        if term == item:
            break
        i += 1
    else:
        i = -1
    return i, stack


D['index_of'] = index_of


    

In [4]:

    

J('[0 2 7 0] 7 index_of')


    

    




2

In [5]:

    

J('[0 2 7 0] 23 index_of')


    

    




-1

In [6]:

    

from joy.utils.stack import iter_stack, list_to_stack


@SimpleFunctionWrapper
def distribute(stack):
    '''Starting at index+1 distribute count "blocks" to the "banks" in the sequence.

    [...] count index distribute
    ----------------------------
               [...]

    '''
    index, (count, (sequence, stack)) = stack
    assert count >= 0
    cheat = list(iter_stack(sequence))
    n = len(cheat)
    assert index < n
    cheat[index] = 0
    while count:
        index += 1
        index %= n
        cheat[index] += 1
        count -= 1
    return list_to_stack(cheat), stack


D['distribute'] = distribute


    

In [7]:

    

J('[0 2 7 0] dup max [index_of] nullary distribute')


    

    




[2 4 1 2]

In [8]:

    

J('[2 4 1 2] dup max [index_of] nullary distribute')


    

    




[3 1 2 3]

In [9]:

    

J('[3 1 2 3] dup max [index_of] nullary distribute')


    

    




[0 2 3 4]

In [10]:

    

J('[0 2 3 4] dup max [index_of] nullary distribute')


    

    




[1 3 4 1]

In [11]:

    

J('[1 3 4 1] dup max [index_of] nullary distribute')


    

    




[2 4 1 2]

In [12]:

    

define('direco == dip rest cons')


    

In [13]:

    

define('G == [direco] cons [swap] swoncat cons')


    

In [14]:

    

define('make_distributor == [dup dup max [index_of] nullary distribute] G')


    

In [15]:

    

J('[0 2 7 0] make_distributor 6 [x] times pop')


    

    




[0 2 7 0] [2 4 1 2] [3 1 2 3] [0 2 3 4] [1 3 4 1] [2 4 1 2]

In [16]:

    

define('count_states == [] swap x [pop index_of 0 >=] [popop size] [[swons] dip x] primrec')


    

In [17]:

    

define('AoC2017.6 == make_distributor count_states')


    

In [18]:

    

J('[0 2 7 0] AoC2017.6')


    

    




5

In [19]:

    

J('[1 1 1] AoC2017.6')


    

    




4

In [20]:

    

J('[8 0 0 0 0 0] AoC2017.6')


    

    




15