adventofcode2022/day22/sol.py

map = []
moves = ""
with open("input") as f:
    for line in f:
        if line == "\n":
            break
        map.append(line.rstrip("\n"))
    moves = f.readline().strip()

F = {
    0: (+1, 0),
    1: (0, +1),
    2: (-1, 0),
    3: (0, -1),
}

#assert len(set(len(l) for l in map)) == 1

class Map:
    def __init__(self, map):
        self.map = map
        self.starts = {}
        for row in range(len(self.map)):
            i = 0
            while self.map[row][i] == ' ':
                i += 1
            self.starts[row] = i
        self.row = 0
        self.col = self.starts[0]
        self.face = 0

        #   9'
        #   1 2
        # \ 4 \
        # 6 7
        # 9 \
        self.region_map = {
            #   R      D      L     U
            1: [(2,0), (4, 0), (6,2), (9, 1)],
            4: [(2,-1), (7,0), (6,-1), (1, 0)],
            7: [(2,2), (9,+1), (6,0), (4,0)],
            6: [(7,0), (9,0), (1,2), (4,+1)],
            9: [(7,-1), (2,0), (1,-1), (6,0)],
            2: [(7,2), (4,+1), (1, 0), (9,0)],
        }

        ok = True
        for f in range(4):
            for r in self.region_map:
                orig = (r,f)
                s = repr(orig)
                for _ in range(4):
                    r, h = self.region_map[r][f]
                    f = (f+h)%4
                    s += "-> {} {}".format(r, f)
                if (r,f) != orig:
                    print("!!", s)
                    ok = False
        assert ok, "region topography failure"

    def nextTile(self, x, y, face):
        # 0 - E
        # 1 - S
        # 2 - W
        # 3 - N
        dx, dy = F[face]
        r = self.region(x,y)
        if 0 <= (x%50 + dx) < 50 and 0 <= (y%50 + dy) < 50:
            x, y = x+dx, y+dy
        else:
            new_r, rotate = self.region_map[r][face]
            x = (x+dx) % 50
            y = (y+dy) % 50

            if rotate == 0:
                pass
            elif rotate == -1:
                x, y = y, 50-x-1
            elif rotate == 1:
                x, y = 50-y-1, x
            elif rotate == 2:
                x, y = 50-x-1, 50-y-1
            x, y = self.in_region(x, y, new_r)
            face = (face + rotate) % 4
        c = self.map[y][x]
        assert c != ' '
        return x, y, face, c

    @staticmethod
    def in_region(x, y, r):
        """returns the absolute coords if the local (x,y) in region r"""
        x %= 50
        y %= 50
        rx = r % 3
        ry = r // 3
        return (rx*50 + x), (ry*50 + y)

    @staticmethod
    def region(x, y):
        return y//50 * 3 + x//50

    def warp(x,y,face):
        r = self.region(x,y)
        s = 0

        if dx:
            x += dx
            if x < self.starts[y]:
                x = len(self.map[y])-1
            elif x >= len(self.map[y]):
                x = self.starts[y]

        if dy:
            for _ in range(999):
                y += dy
                if y < 0:
                    y = len(self.map)-1
                elif y >= len(self.map):
                    y = 0
                if x > len(self.map[y]) or self.map[y][x] == ' ':
                    continue
                break

        assert self.map[y][x] != ' '
        return x, y, self.map[y][x]

    def turnLeft(self):
        self.face = (self.face - 1) % 4
    def turnRight(self):
        self.face = (self.face + 1) % 4
    def walk(self, n):
        while n > 0:
            x,y,f,c = self.nextTile(self.col, self.row, self.face)
            if c == '#':
                break
                pass#break
            self.row = y
            self.col = x
            self.face = f
            #self.map[y][x] = '>v<^'[self.face]
            n -= 1
        print(self.row+1, self.col+1)

    def pos(self):
        return self.row+1, self.col+1

    def score(self):
        r, c = self.pos()
        return r*1000 + c*4 + self.face

print(moves)

m = Map(map)

for _ in range(4):
    #m.walk(50)
    print("---")

#blah
i = 0
while i < len(moves):
    if moves[i].isdigit():
        j = i+1
        while j < len(moves) and moves[j].isdigit():
            j += 1
        n = int(moves[i:j])
        m.walk(n)
        i = j
    elif moves[i] == 'L':
        m.turnLeft()
        i += 1
    elif moves[i] == 'R':
        m.turnRight()
        i += 1
    else:
        print("invalid move", moves[i], "at", i)
        i += 1

print(m.row, m.col)
print(m.score())