91 lines
1.8 KiB
Python
91 lines
1.8 KiB
Python
from collections import deque
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from lib import get_data
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from lib import Grid2D
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data = """###############
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#...#...#.....#
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#.#.#.#.#.###.#
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#S#...#.#.#...#
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#######.#.#.###
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#######.#.#...#
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#######.#.###.#
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###..E#...#...#
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###.#######.###
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#...###...#...#
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#.#####.#.###.#
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#.#...#.#.#...#
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#.#.#.#.#.#.###
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#...#...#...###
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###############
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"""
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data = get_data(__file__)
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g = Grid2D(data)
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(start,) = g.find("S")
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(end,) = g.find("E")
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cost = 0
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sd = dict()
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de = dict()
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queue = deque([(start[0], start[1], 0)])
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seen = set()
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while queue:
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r, c, cost = queue.popleft()
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if (r, c) in sd:
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continue
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sd[(r, c)] = cost
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if (r, c) == end:
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break
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for r, c in g.neighbors_ort((r, c)):
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if g[(r, c)] != "#":
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queue.append((r, c, cost + 1))
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seen = set()
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queue = deque([(end[0], end[1], 0)])
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while queue:
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r, c, cost = queue.popleft()
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if (r, c) in de:
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continue
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de[(r, c)] = cost
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if (r, c) == start:
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break
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for r, c in g.neighbors_ort((r, c)):
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if g[(r, c)] != "#":
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queue.append((r, c, cost + 1))
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for max_steps in [2, 20]:
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cheats = set()
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for cr, cc in g.find("S."):
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start = cr, cc, 0
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seen = set()
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queue = deque([start])
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while queue:
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r, c, steps = queue.popleft()
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if steps > max_steps:
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continue
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if (r, c) in seen:
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continue
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seen.add((r, c))
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if g[(r, c)] != "#":
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ncost = sd[(cr, cc)] + steps + de[(r, c)]
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if cost - ncost >= 100:
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cheats.add((cr, cc, r, c))
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for dr, dc in [(-1, 0), (0, 1), (1, 0), (0, -1)]:
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nr, nc = r + dr, c + dc
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if g.contains((nr, nc)):
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queue.append((nr, nc, steps + 1))
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print(len(cheats))
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