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@ -1,4 +1,5 @@
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import string
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import sys
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from grid import Grid
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from vector import v2a
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@ -9,9 +10,6 @@ EX1 = [
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"#b.A.@.a#",
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"#########",
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]
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# reqs:
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# a: []
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# b: [a]
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EX2 = [
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"########################",
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"#f.D.E.e.C.b.A.@.a.B.c.#",
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@ -19,41 +17,48 @@ EX2 = [
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"#d.....................#",
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"########################",
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]
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# reqs:
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# a: []
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# b: [a]
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# c: [b]
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# d: [b]
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# e: [a, c]
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# f: [a, c, e, d]
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#
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# - get a
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# - get b
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# - get c or d?
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# - get c
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# - get d or e?
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# - d
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def main():
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with open("day18.txt", "rt") as input_file:
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lines = input_file.readlines()
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lab = Lab(lines=EX1)
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lab = Lab(lines=lines)
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lab.dumb_print()
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lab.find_positions()
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pos = lab.start
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missing_keys = list(lab.key_pos.keys())
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obtained_keys = set("a")
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while missing_keys:
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for key, bt in lab.get_all_backtracks(pos).items():
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steps, reqs, founds = bt
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if len(reqs - obtained_keys) == 0:
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print(key, "is accessible")
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break
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states = [(lab.start, frozenset(), 0)]
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state_cache = Grid(value_factory=dict)
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num_keys = len(lab.key_pos)
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min_steps = 2**32
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num_processed = 0
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while states:
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num_processed += 1
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pos, obtained, total_steps = states.pop(0)
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if len(obtained) == num_keys:
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print(f"All keys obtained in {total_steps}.")
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min_steps = min(min_steps, total_steps)
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continue
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for key_name, bt in lab.get_missing_backtracks(pos, keys=obtained).items():
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steps, required, found = bt
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if len(required - obtained) > 0:
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continue
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next_pos = lab.key_pos[key_name]
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next_obtained = obtained | found | {key_name}
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next_steps = total_steps + steps
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old_bests = state_cache.getv(next_pos[0], next_pos[1])
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if next_obtained not in old_bests or old_bests[next_obtained] > next_steps:
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print("o", end="")
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states.append((next_pos, next_obtained, next_steps))
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old_bests[next_obtained] = next_steps
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print(".", end="")
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if num_processed % 100 == 0:
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print(f"[{num_processed}/{len(states)}]", end="")
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sys.stdout.flush()
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print(f"Minimal number of steps to get all keys: {min_steps}.")
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class Lab(Grid):
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@ -77,13 +82,18 @@ class Lab(Grid):
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self.door_pos[v] = (x, y)
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self.setv(self.start[0], self.start[1], Lab.TILE_PATH)
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def get_all_backtracks(self, start):
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return {
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kname: self.backtrack(self.path(start, kpos), kpos, start)
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for kname, kpos in self.key_pos.items()
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}
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def path(self, s, e):
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def get_missing_backtracks(self, start, keys=set()):
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backtracks = {}
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for kname, kpos in self.key_pos.items():
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if kname in keys:
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continue
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path = self.path(start, kpos, keys=keys)
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if path is None:
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continue
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backtracks[kname] = self.backtrack(path, kpos, start)
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return backtracks
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def path(self, s, e, keys=set()):
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discovered = Grid(value_factory=bool)
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discovered.setv(s[0], s[1], True)
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parents = {}
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@ -96,12 +106,14 @@ class Lab(Grid):
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for near_pos, near_tile in nears.items():
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if near_tile == Lab.TILE_WALL:
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continue
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if near_tile in string.ascii_uppercase and near_tile.lower() not in keys:
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continue
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if discovered.getv(near_pos[0], near_pos[1]):
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continue
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discovered.setv(near_pos[0], near_pos[1], True)
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parents[near_pos] = pos
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q.append(near_pos)
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return parents
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return None
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def backtrack(self, parents, pos, end):
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count = 0
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@ -115,7 +127,7 @@ class Lab(Grid):
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requirements.add(tile.lower())
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elif tile in string.ascii_lowercase:
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keys_found.add(tile)
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return count, requirements, keys_found
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return count, requirements, frozenset(keys_found)
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if __name__ == "__main__":
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