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from sys import stdin
from math import *
import re
data = stdin.readlines()
path = data[-1]
data = [list(line.strip('\n')) for line in data[:-2]]
area = len([c for c in sum(data, start=[]) if not c.isspace()])
sideLen = int(sqrt(area / 6))
tiny = [a[::sideLen] for a in data[::sideLen]]
def dot(a, b):
assert len(a) == len(b)
return sum([i*j for i,j in zip(a, b)])
def matmul(a, b):
# matrix storage is flipped
# that is - [[1,2,3]] is a column vector
assert len(a) == len(b[0])
m = [[0] * len(a[0]) for _ in b]
for i in range(len(m[0])):
for j in range(len(m)):
m[j][i] = dot(b[j], [col[i] for col in a])
return m
def matadd(a, b):
assert len(a) == len(b)
assert len(a[0]) == len(b[0])
m = [[0] * len(a[0]) for _ in a]
for i in range(len(m[0])):
for j in range(len(m)):
m[j][i] = a[j][i] + b[j][i]
return m
def matmulsc(a, b):
return [[n * b for n in col] for col in a]
def only(a):
assert len(a) == 1
return a[0]
def gen3Drots():
# base, 3 axis
rots = [[[0, 1, 0],
[-1, 0, 0],
[0, 0, 1]],
[[0, 0, 1],
[0, 1, 0],
[-1, 0, 0]],
[[1, 0, 0],
[0, 0, 1],
[0, -1, 0]]]
# gen flipped
rots2 = []
for rot in rots:
rots2.append(rot)
rots2.append(matmul(matmul(rot, rot), rot))
# ensure they're proper rotations
for rot in rots2:
rot2 = rot
for _ in range(4):
rot2 = matmul(rot, rot2)
assert rot == rot2
return rots2
rots = gen3Drots()
# vertexes of each face's corners
# the edge (wall[f]; wall[f+1]) is the edge towards facing f
wall = [[[ 1, -1, 1]],
[[ 1, 1, 1]],
[[-1, 1, 1]],
[[-1, -1, 1]]]
def step(wall, f):
def edge(f):
v1 = wall[f%4]
v2 = wall[(f+1)%4]
return matmulsc(matadd(v1, v2), 0.5)
shared = edge(f) # the shared edge
prev = edge(f+2) # the edge opposite to shared; will become shared after rot
rot = only([rot for rot in rots if matmul(rot, prev) == shared])
wall = [matmul(rot, v) for v in wall]
return rot, wall
# generate projections from face of 3d cube to 2d square
def genProjs():
from itertools import permutations
projs = []
for a in [-1, 1]:
for b in [-1, 1]:
base = [[a, 0], [0, b], [0, 0]]
for p in permutations(base):
p = list(p)
projs.append(p)
return projs
projs = genProjs()
def planestep(x, y, f):
x += [1, 0, -1, 0][f]
y += [0, 1, 0, -1][f]
if not 0 <= y < len(data): return None
if not 0 <= x < len(data[y]): return None
if data[y][x].isspace(): return None
return (x, y, f)
def cubestep(x, y, f):
if planestep(x, y, f) != None: return planestep(x, y, f)
bwall = [[[ 1, -1, 1]],
[[ 1, 1, 1]],
[[-1, 1, 1]],
[[-1, -1, 1]]]
def edge(wall, f):
v1 = wall[f%4]
v2 = wall[(f+1)%4]
return matmulsc(matadd(v1, v2), 0.5)
shared = edge(bwall, f)
visited = set()
def rec(bx, by, bwall):
nonlocal visited
visited.add((bx, by))
for f in range(4):
wx = bx + [1, 0, -1, 0][f] * sideLen
wy = by + [0, 1, 0, -1][f] * sideLen
if (wx, wy) in visited: continue
if not 0 <= wy < len(data): continue
if not 0 <= wx < len(data[wy]): continue
if data[wy][wx].isspace(): continue
visited.add((wx, wy))
_, wall = step(bwall, f)
for f in range(4):
e = edge(wall, f)
if e == shared:
return (wx, wy, wall)
r = rec(wx, wy, wall)
if r != None:
return r
wx, wy, wall = rec(x, y, bwall)
# bwall is the base face, wall is the face we move to
# wx, wy are some coordinates inside of the face - convert to upleft corner
wx = wx // sideLen * sideLen
wy = wy // sideLen * sideLen
# find the correct projection from cube space to input space
def isGoodProj(p):
for vid in range(4):
v1 = matmul(p, wall[vid])
v2 = [bwall[vid][0][:2]]
if v1 != v2: return False
return True
proj = only([p for p in projs if isGoodProj(p)])
# coordinates in the wall before rotation
bx = (x + [1, 0, -1, 0][f]) % sideLen
by = (y + [0, 1, 0, -1][f]) % sideLen
# vertex on starting face of cube
v = [[bx - (sideLen-1)/2, by - (sideLen-1)/2, 1]]
# rotate to new face
rot, _ = step(bwall, f)
v = matmul(rot, v)
# project to input space
v = matmul(proj, v)
v = [[int(f + (sideLen+1)/2) - 1 for f in v[0]]] # wall coords
# find new facing
# shared - old facing relative to original wall
dv = matmul(proj, matmul(rot, shared))
def dvToFacing(dv):
for f in range(4):
dx = [1, 0, -1, 0][f]
dy = [0, 1, 0, -1][f]
if dv[0][0] == dx and dv[0][1] == dy:
return f
raise "fuck"
return wx + v[0][0], wy + v[0][1], dvToFacing(dv)
def vis():
for line in data:
print(''.join(line))
def move(x, y, f, d):
for _ in range(d):
nx, ny, nf = cubestep(x, y, f)
if data[ny][nx] == '#':
break
data[y][x] = ">v<^"[f]
x, y, f = nx, ny, nf
return x, y, f
def partTwo():
x = data[0].index('.')
y = 0
f = 0
for c in re.findall("\d+|[A-Z]", path):
if c == 'L': f = (f - 1) % 4
elif c == 'R': f = (f + 1) % 4
else:
x, y, f = move(x, y, f, int(c))
return (y+1) * 1000 + (x+1) * 4 + f
print(partTwo())
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