Anders Englöf Ytterström
9dc3f16766
BFS baby. FIRST_BLOCKED was found manually using code from pt 1 to perform a binary search.
90 lines
1.8 KiB
Python
90 lines
1.8 KiB
Python
from collections import deque
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from output import ints, D
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def solve(data):
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grid = [tuple(ints(line)[::-1]) for line in data.splitlines()]
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sample_size = 1024
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H = 71
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W = 71
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E = H - 1, W - 1
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p1 = None
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p2 = None
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FIRST_BLOCKED = 2974
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for sample_size in [1024, FIRST_BLOCKED]:
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answer = None
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Q = deque([(0, 0, 0)])
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seen = set()
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while Q:
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y, x, w = Q.popleft()
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if (y, x) in seen:
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continue
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seen.add((y, x))
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if (y, x) == E:
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answer = w
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for dy, dx in D:
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if not (0 <= y + dy < H and 0 <= x + dx < W):
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continue
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if (y + dy, x + dx) in grid[:sample_size]:
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continue
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Q.append((y + dy, x + dx, w + 1))
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if not answer:
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r, c = grid[sample_size - 1]
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p2 = f"{c},{r}"
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else:
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p1 = answer
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return p1, p2
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if __name__ == "__main__":
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import os
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# use dummy data
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inp = """
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5,4
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4,2
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4,5
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3,0
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2,1
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6,3
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2,4
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1,5
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0,6
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3,3
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2,6
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5,1
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1,2
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5,5
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2,5
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6,5
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1,4
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0,4
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6,4
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1,1
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6,1
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1,0
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0,5
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1,6
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2,0
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""".strip()
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# uncomment to instead use stdin
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# import sys; inp = sys.stdin.read().strip()
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# uncomment to use AoC provided puzzle input
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with open("./input/18.txt", "r") as f:
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inp = f.read().strip()
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# uncomment to do initial data processing shared by part 1-2
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p1, p2 = solve(inp)
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print(p1)
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os.system(f"echo {p1} | wl-copy")
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print(p2)
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os.system(f"echo {p2} | wl-copy")
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# uncomment and replace 0 with actual output to refactor code
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# and ensure nonbreaking changes
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# assert p1 == 0
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# assert p2 == 0
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