advent2020/twentythree.py

#!/usr/bin/env python3
from functools import reduce
from itertools import cycle
import re, sys
import math
import numpy as np

def dprint(*args):
    sep = False
    for arg in args:
        if sep:
            print('--------')
        sep = True
        for a, b in arg.items():
            print('%10s: %s' % (a, ','.join(b)))
    print()

def cup(base, rest):
    # find index of next cup to pick up
    trial = chr(ord(base) - 1) if base > '1' else '9'
    try:
        return rest.index(trial)
    except: # not there
        return cup(trial, rest)

def getoff(circle, offset):
    # undo our offset
    return (circle + circle)[9 - offset:18 - offset]

def printoff(circle, offset):
    print('%s (%d)' % (getoff(circle, offset), offset))

def printafterone(circle):
    # lol we don't even need the offset
    oneidx = circle.index('1')
    print(circle[oneidx+1:] + circle[:oneidx])

def printnice(first, three, six, dest, i):
    # ugh
    print('-- move %d --' % i)
    print('cups: (%s)%s' % (first, ''.join(' %s ' % c for c in three + six)))
    print('pick up: %s' % ', '.join(three))
    print('destination: %s' % dest)
    print()

def move(circle, offset, i=1):
    # don't keep track of the selected; just keep it at the left
    # instead keep track of how far we've shifted the circle left
    # (modulo 9, as if you care)
    # ANYWAY, our selected cup is always in first position, so grab the three next
    selected, pickup, remain = circle[0], circle[1:4], circle[4:]
    dest = cup(selected, remain)
    printnice(selected, pickup, remain, remain[dest], i) # jfc
    # build the new circle
    return (''.join(
        [*remain[:dest],
            remain[dest],
            *pickup,
            *remain[dest+1:],
            selected,
            ]),
        (offset + 1 + dest) % 9)

def subone(sel, three, size):
    ret = sel - 1
    if ret == 0:
        ret = size
    if ret in three:
        return subone(ret, three, size)
    else:
        return ret

def messwith(l, r, sel, size=1000000):
    #print('selected:', sel)
    three = r[sel], r[r[sel]], r[r[r[sel]]]
    #print('pick up:', three)
    # DANGLING: r[sel], l[r[sel]] (change in opposite order of course),
    # ... r[three[-1]], l[ibid],
    # ALSO MODIFY: r[dest], l[r[dest]] (again change in opposite order)
    dest = subone(sel, three, size)
    #print('destination:', dest)
    # i do not like python
    #print('r[%s] = %s' % (sel, r[three[-1]]))
    #print('l[%s] = %s' % (r[sel], dest))
    #print('r[%s] = %s' % (three[-1], r[dest]))
    #print('l[%s] = %s' % (r[three[-1]], sel))
    #print('r[%s] = %s' % (dest, three[0]))
    #print('l[%s] = %s' % (r[dest], three[-1]))
    #print('set this to 1, please:', l[r[dest]], 'btw', r[dest])
    src_r_idx = sel
    src_l_idx = r[three[-1]]
    dst_r_idx = dest
    dst_l_idx = r[dest]
    three_r_idx = three[-1]
    three_l_idx = three[0] # which indeed is r[sel], yes
    r[src_r_idx] = src_l_idx
    l[src_l_idx] = src_r_idx
    r[dst_r_idx] = three_l_idx
    l[dst_l_idx] = three_r_idx
    r[three_r_idx] = dst_l_idx
    l[three_l_idx] = dst_r_idx
    #print()
    #print('left:', l)
    return r[sel]

def rightof(r, i, rem):
    if rem == 0:
        return []
    return [r[i], ] + rightof(r, r[i], rem - 1)

def printall(r, sel, size):
    print('cups:', ''.join('%s%s%s' % (
        '(' if x == sel else ' ',
        str(x),
        ')' if x == sel else ' ')
        for x in rightof(r, 1, size)))

fn = sys.argv[1] if len(sys.argv) > 1 else 'input%s' % 23
with open(fn) as f:

    offset, circle = 0, f.read().strip()
    finito = reduce(lambda a, b: move(a[0], a[1], i=b+1), range(100), (circle, offset)) # lol
    printoff(*finito)
    printafterone(finito[0])

    # well, we'll have to be more creative here
    size = int(sys.argv[2] if len(sys.argv) > 2 else 1e6)
    # first, redo part 1
    orbit = np.linspace(1, size, size, dtype=int)
    for i, c in enumerate(circle):
        orbit[i] = int(c)
    print(orbit)
    left = np.zeros(size + 1, dtype=int) # 1-indexed, so "pad"
    right = np.zeros(size + 1, dtype=int)
    for i, c in enumerate(orbit):
        left[c] = orbit[(i+size-1)%size]
        right[c] = orbit[(i+1)%size]
    print(left[1:11], '<>', right[1:11])
    print()

    selidx = orbit[0]
    rounds = int(sys.argv[3] if len(sys.argv) > 2 else 1e7)
    for i in range(rounds):
        #print('-- round %d --' % (i + 1))
        #printall(right, selidx, size)
        selidx = messwith(left, right, selidx, size=size)
        if not (i % math.ceil(rounds / 10)):
            print(left[1:], '<>', right[1:])
            print('%d to go' % (rounds - i))
    print('-- final --')
    print(left[1:], '<>', right[1:])
    #printall(right, selidx, size)

    # ok, now find cups on SIDE.
    bill = right[1]
    bob = right[bill]
    print('%d * %d =\n%d' % (bill, bob, (bill * bob)))