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path: root/20_2020.py
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import fileinput
import re
from copy import deepcopy
from collections import defaultdict
import math

R = 10
C = 10


def rotate(T):
    TR = len(T)
    TC = len(T[0])
    # takes (r,c) to (c, R-1-r)
    RET = [["?" for _ in range(TR)] for _ in range(TC)]
    for r in range(TR):
        for c in range(TC):
            RET[c][TR - 1 - r] = T[r][c]
    return RET


def flip(T):
    return list(reversed(T))


def flip2(T):
    return [list(reversed(row)) for row in T]


def poss(T):
    ans = set()
    flips = [deepcopy(T), flip(T)]  # , flip2(T), flip(flip2(T))]
    for _ in range(4):
        for i in range(len(flips)):
            ans.add(tuple([tuple(row) for row in flips[i]]))
            flips[i] = rotate(flips[i])
    return ans


L = list([l.strip() for l in fileinput.input()])
L.append("")
G = {}
name = None
piece = []
for l in L:
    if "Tile" in l:
        name = int(l.split()[1][:-1])
    elif l:
        piece.append(list(l))
    else:
        G[name] = piece
        piece = []

# for k,T in G.items():
#    print(k)
#    for row in T:
#        print(''.join(row))

EDGE = {}
for k, T in G.items():
    left = []
    right = []
    top = []
    bottom = []
    for r in range(R):
        left.append(T[r][0])
        right.append(T[r][R - 1])
    for c in range(C):
        top.append(T[0][c])
        bottom.append(T[R - 1][c])
    edges = [tuple(x) for x in [left, right, top, bottom]]
    EDGE[k] = set([x for x in edges] + [tuple(reversed(x)) for x in edges])


E = defaultdict(set)

# Assumes if two pieces have identical boundaries they will actually be adjacent in the final puzzle
start = None
ans = 1
for k1, ET in EDGE.items():
    nbrs = 0
    for k2, EU in EDGE.items():
        if k1 != k2:
            if ET & EU:
                E[k1].add(k2)
    if len(E[k1]) == 2:
        start = k1
        ans *= k1
print(ans)

GR = int(math.sqrt(len(EDGE)))
GC = int(math.sqrt(len(EDGE)))
USED = set()
assert len(EDGE) == GR * GC
PLACE = [[None for _ in range(GR)] for _ in range(GC)]
PLACE[0][0] = start
PLACE[0][1], PLACE[1][0] = E[start]
USED.add(PLACE[0][0])
USED.add(PLACE[0][1])
USED.add(PLACE[1][1])

D = [(-1, 0), (0, 1), (1, 0), (0, -1)]

#####
####
###
##
#

while True:
    if len(USED) == GR * GC:
        break
    for r in range(GR):
        for c in range(GC):
            if PLACE[r][c] is not None:
                continue
            opts = set([k for k in E.keys() if k not in USED])
            for dr, dc in D:
                rr, cc = r + dr, c + dc
                if 0 <= rr < GR and 0 <= cc < GC and PLACE[rr][cc]:
                    opts = opts & E[PLACE[rr][cc]]
            if len(opts) == 1:
                chosen = list(opts)[0]
                PLACE[r][c] = chosen
                assert chosen not in USED
                USED.add(chosen)


# Does the boundary of p1 match p2, assuming p2 is in the direction (dr,dc)?
def matches(p1, p2, dr, dc):
    if dr == -1:  # up, so top of p1 should match bottom of p2
        for c in range(C):
            if p1[0][c] != p2[R - 1][c]:
                return False
        return True
    elif dc == 1:  # right, so right of p1 should match left of p2
        for r in range(R):
            if p1[r][C - 1] != p2[r][0]:
                return False
        return True
    elif dr == 1:
        for c in range(C):
            if p1[R - 1][c] != p2[0][c]:
                return False
        return True
    elif dc == -1:
        for r in range(R):
            if p1[r][0] != p2[r][C - 1]:
                return False
        return True
    else:
        assert False


PIECES = [[None for _ in range(GR)] for _ in range(GC)]
for r in range(GR):
    for c in range(GC):
        opts = poss(G[PLACE[r][c]])
        for dr, dc in D:
            rr, cc = r + dr, c + dc
            if 0 <= rr < GR and 0 <= cc < GC:
                ok_nbr = set()
                opts_nbr = poss(G[PLACE[rr][cc]])
                for o1 in opts:
                    for o2 in opts_nbr:
                        if matches(o1, o2, dr, dc):
                            ok_nbr.add(o1)
                opts = opts & ok_nbr
        # Assumes that every piece has only one orientation that can match its neighbors
        assert len(opts) == 1
        PIECES[r][c] = list(opts)[0]

for r in range(GR):
    for c in range(GC):
        for dr, dc in D:
            rr, cc = r + dr, c + dc
            if 0 <= rr < GR and 0 <= cc < GC:
                p1 = PIECES[r][c]
                p2 = PIECES[rr][cc]
                assert matches(p1, p2, dr, dc)

IMAGE = [["?" for _ in range(GC * (C - 2))] for _ in range(GR * (R - 2))]
for r in range(GR):
    for c in range(GC):
        T = PIECES[r][c]
        assert T in poss(G[PLACE[r][c]])
        for rr in range(1, len(T) - 1):
            for cc in range(1, len(T[rr]) - 1):
                IMAGE[r * (R - 2) + (rr - 1)][c * (C - 2) + (cc - 1)] = T[rr][cc]

M = ["                  # ", "#    ##    ##    ###", " #  #  #  #  #  #   "]
MR = len(M)
MC = len(M[0])
for row in M:
    assert len(row) == MC

IR = len(IMAGE)
IC = len(IMAGE[0])
assert len(IMAGE) == IR
for row in IMAGE:
    assert len(row) == IC

for IM in poss(IMAGE):
    assert len(IM) == IR
    assert len(IM[0]) == IC
    IS_M = [[False for _ in range(len(IM[0]))] for _ in range(len(IM))]
    has_monster = False
    for r in range(IR):
        for c in range(IC):
            is_monster = True
            for mr in range(MR):
                for mc in range(MC):
                    if not (0 <= r + mr < IR and 0 <= c + mc < IC):
                        is_monster = False
                    else:
                        if M[mr][mc] == "#" and IM[r + mr][c + mc] != "#":
                            is_monster = False
            if is_monster:
                has_monster = True
                for mr in range(MR):
                    for mc in range(MC):
                        if M[mr][mc] == "#":
                            IS_M[r + mr][c + mc] = True
    # Assumes only one orientation has sea monsters
    if has_monster:
        ans = 0
        for r in range(IR):
            for c in range(IC):
                if IM[r][c] == "#" and not IS_M[r][c]:
                    ans += 1
        print(ans)