Add an incredibly shoddy day 20... finally, it just werks

d20.py

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+#!/usr/bin/env python3
+
+from sys import argv
+from math import sqrt
+
+tiles = {}
+for tile in map(lambda x: x.splitlines(), open(argv[1]).read().strip().split("\n\n")):
+    tiles[int(tile[0][5:-1])] = "".join(tile[1:])
+
+size = int(sqrt(len(tiles)))
+tsize = int(sqrt(len(next(iter(tiles.values())))))
+
+sides = {}
+sides_rev = {}
+for tile in tiles:
+    data = tiles[tile]
+    up = data[0:tsize]
+    down = data[tsize ** 2 - tsize:tsize ** 2]
+    left = ""
+    right = ""
+    for x in range(tsize):
+        left += data[tsize * x]
+        right += data[tsize * x + tsize - 1]
+    up = up[::-1]
+    right = right[::-1]
+
+    sides[tile] = [
+        up, left, down, right,
+        up[::-1], left[::-1], down[::-1], right[::-1]
+    ]
+    for i, side in enumerate(sides[tile]):
+        if side not in sides_rev:
+            sides_rev[side] = []
+        sides_rev[side].append((tile, i))
+
+tiles_noconn = {}
+for side in sides_rev:
+    if len(sides_rev[side]) == 1:
+        tile, orien = sides_rev[side][0]
+        if tile not in tiles_noconn:
+            tiles_noconn[tile] = []
+        tiles_noconn[tile].append(orien)
+tiles_corner = [i for i, noconn in tiles_noconn.items() if len(noconn) == 4]
+print(tiles_corner[0] * tiles_corner[1] * tiles_corner[2] * tiles_corner[3])
+
+# Figure out the orientation of the top-left corner tile we pick
+orien = tiles_noconn[tiles_corner[0]]
+if 3 in orien and 0 in orien:
+    orien = 3
+else:
+    orien = min(orien)
+corner = (tiles_corner[0], orien)
+
+def get_orien(base, add):
+    if base & 4:
+        add = 4 - add
+    return ((base + add) & 3) | (base & 4)
+
+# Create a connection graph
+conn = {}
+for side in sides_rev.values():
+    if len(side) != 2:
+        continue
+    conn[side[0]] = side[1]
+    conn[side[1]] = side[0]
+
+# Put the grid together, starting from the top-left corner, going right then down
+grid = []
+for y in range(size):
+    if y:
+        tile_top, orien_top = grid[y-1][0]
+        orien_top = get_orien(orien_top, 2)
+        tile, orien = conn[(tile_top, orien_top)]
+        orien ^= 4
+        row = [(tile, orien)]
+    else:
+        row = [corner]
+
+    for x in range(1, size):
+        tile_left, orien_left = row[x-1]
+        orien_left = get_orien(orien_left, 3)
+        tile, orien = conn[(tile_left, orien_left)]
+        orien = get_orien(orien, -1)
+        orien ^= 6
+        row.append((tile, orien))
+
+    grid.append(row)
+
+def rotate(tile, orien):
+    # Flip the tile if necessary
+    if orien >= 4:
+        tile = [row[::-1] for row in tile]
+        orien = (4 - orien) % 4
+    # Rotate the tile
+    for x in range(orien):
+        tile = [[tile[len(iy) - x - 1][y] for x, ix in enumerate(iy)] for y, iy in enumerate(tile)]
+    return tile
+
+# Create image
+ssize = tsize - 2
+image = [[0] * size * ssize for x in range(size * ssize)]
+for y, row in enumerate(grid):
+    y *= ssize
+    for x, (tile, orien) in enumerate(row):
+        x *= ssize
+
+        # Convert tile data into grid, strip the edges
+        tile = [tiles[tile][x + 1:x + tsize - 1] for x in range(tsize, tsize ** 2 - tsize, tsize)]
+        tile = rotate(tile, orien)
+
+        # Store into image
+        for iy, irow in enumerate(tile):
+            for ix, c in enumerate(irow):
+                image[y + iy][x + ix] = c
+
+# Find monsters
+monster = """
+                  #
+#    ##    ##    ###
+ #  #  #  #  #  #
+"""
+monster = [(y,x) for y, line in enumerate(monster[1:-1].split("\n")) for x, char in enumerate(line) if char == "#"]
+monster_h = 3
+monster_w = 20
+
+for orien in range(8):
+    cur_image = rotate(image, orien)
+    count = 0
+    for y in range(size * ssize - monster_h):
+        for x in range(size * ssize - monster_w):
+            for m in monster:
+                if cur_image[m[0] + y][m[1] + x] != "#":
+                    break
+            else:
+                for m in monster:
+                    cur_image[m[0] + y][m[1] + x] = "O"
+                count += 1
+    if count:
+        break
+
+# Tally roughness
+print(sum(1 for row in cur_image for char in row if char == "#"))
+
+# for row in cur_image:
+    # print("".join(row))

d20_output.txt

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+66020135789767
+1537